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VLT narrow-band photometry in the Lyman continuum of two galaxies at z~3 Limits to the esca

VLT narrow-band photometry in the Lyman continuum of two galaxies at z~3 Limits to the esca
VLT narrow-band photometry in the Lyman continuum of two galaxies at z~3 Limits to the esca

a r X i v :a s t r o -p h /0501382v 2 14 F e

b 2005

Astronomy &Astrophysics manuscript no.ms˙twocol February 2,2008

(DOI:will be inserted by hand later)

VLT narrow-band photometry in the Lyman continuum of two

galaxies at z ~3?

Limits to the escape of ionizing ?ux

A.K.Inoue ??1,2,3,I.Iwata 3,4???,J.-M.Deharveng 1,V.Buat 1,and D.Burgarella 1

1

Laboratoire d’Astrophysique de Marseille,Traverse du Siphon,BP 8,13376Marseille,CEDEX 12,France

e-mail:akio.inoue@oamp.fr,veronique.buat@oamp.fr,denis.burgarella@oamp.fr,jean-michel.deharveng@oamp.fr 2Department of Physics,Kyoto University,Sakyo-ku,Kyoto 606-8502,Japan 3Department of Astronomy,Kyoto University,Sakyo-ku,Kyoto 606-8502,Japan

4

Subaru Mitaka O?ce (Subaru Telescope),National Astronomical Observatory of Japan,2-21-1Osawa,Mitaka,Tokyo 181-8588,Japan

e-mail:iwata@optik.mtk.nao.ac.jp

Submitted on August 2,2004

Abstract.

We have performed narrow-band imaging observations with the Very Large Telescope,aimed at detecting the Lyman continuum (LC)?ux escaping from galaxies at z ~3.We do not ?nd any signi?cant LC ?ux from our sample of two galaxies in the Hubble Deep Field South,at z =3.170and 3.275.The corresponding lower limits on the F 1400/F 900?ux density (per Hz)ratio are 15.6and 10.2(3-σcon?dence level).After correction for the intergalactic hydrogen absorption,the resulting limits on the relative escape fraction of the LC are compared with those obtained by di?erent approaches,at similar or lower redshifts.One of our two objects has a relative escape fraction lower than the detection reported by Steidel et al.in a composite spectrum of z ~3galaxies.A larger number of objects is required to reach a signi?cant conclusion.Our comparison shows the potential of narrow-band imaging for obtaining the best limit on the relative escape fraction at z ~3.Stacking a signi?cant number of galaxies observed through a narrow-band ?lter would provide constraint on the galactic contribution to the cosmic reionization.

Key words.cosmology:observations —di?use radiation —intergalactic medium —galaxies:photometry —ultraviolet:galaxies

1.Introduction

The observations of the ?nishing and the beginning reionization of intergalactic hydrogen at z ~6and 20(Becker et al.,2001;Kogut et al.,2003)combined with the later reionization of intergalactic He ii (Kriss et al.,2001;Zheng et al.,2004)at z ~3are now placing con-straints on the nature and the evolution of the ultra-violet (UV)background radiation.A dominant contribution of star-forming galaxies is suggested at z >3before the den-sity of luminous quasars become signi?cant.This picture

2Inoue et al.:Upper limit of Lyman continuum escape FUSE in?ve other starburst galaxies(Heckman et al.,

2001).

At high redshifts,the increasing IGM opacity(absorp-

tion of the ionizing radiation by the neutral hydrogen),not

to speak of galaxies becoming fainter,makes the observa-

tions di?cult.Nevertheless,large ground-based telescopes

can enter the competition at z>~3.Steidel et al.(2001)

(hereafter S01)derived a1500?A/900?A observed?ux den-

sity1ratio,(F1500/F900)obs=17.7±3.8from a composite

spectrum of29Lyman break galaxies(LBGs)at a mean

redshift of3.4with Keck/LRIS.By comparison with mod-

els of the UV spectral energy distribution of star-forming

galaxies,the?ux density ratio,corrected for the IGM

opacity,leads to the fraction of escaping LC(900?A)pho-

tons relative to the fraction of escaping non-ionizing UV

(1500?A)photons.This is called the relative escape frac-

tion(f esc,rel)and is di?erent from the?rst de?nition of

the escape fraction(f esc)used above for nearby galaxies.

S01interpreted their results as implying f esc,rel>~50%.

However,not all z~3galaxies emit a signi?cant LC

https://www.sodocs.net/doc/0217794563.html,ing the FORS2spectrograph on the VLT,

Giallongo et al.(2002)(hereafter G02)obtained1-σlower

limits on(F1500/F900)obs four times larger than the value

of S01for two bright LBGs.Heckman et al.(2001)also de-

duced a very low escape fraction for a gravitational lensed

galaxies,MS1512-cB58at z=2.7from the detailed anal-

ysis of interstellar absorption lines.

Observations have not been only spectroscopic.

Imaging of galaxies at z~1with the FUV solar-blind

detector of Space Telescope Imaging Spectrograph(STIS)

have also provided constraints on the?ux below the

Lyman limit(Ferguson,2001;Malkan et al.,2003).In

particular,Malkan et al.(2003)(hereafter M03)have ob-

tained lower limits of(F1500/F700)obs>~150–1000(1-σ),

implying much lower LC escape fraction than in the galax-

ies of S01.Fern′a ndez-Soto et al.(2003)(hereafter FS03)

have used the deep U300images of the Hubble Deep Field

North(HDFN)and reported an average LC escape frac-

tion of no more than4%for27galaxies at redshifts

1.9

have their U300?uxes contaminated by nonionizing UV

photons,their analysis is based on models and indirect.

These con?icting results,as well as the di?culties of

observations at high redshift,have led us to search for pos-

sibilities of improvement.We have?rst examined how the

detection advantage of imaging over spectroscopy is actu-

ally working in the speci?c context of measuring faint LC

radiation.On one hand,spectroscopy allows us to measure

the LC?ux close to the redshifted Lyman limit,where

the average IGM opacity is not yet as large as it would be

at shorter wavelength because of the Lyman valley(e.g.,

M?ller&Jakobsen,1990).On the other hand,broad-band

measurements require a very large correction for the IGM

opacity as we show in the current paper,because the ef-

fective wavelength becomes very short for objects selected

Inoue et al.:Upper limit of Lyman continuum escape 3

0.20.40.60.8124002800320036004000

r e l a t i v e e f f i c i e n c y wavelength [A]

Fig.1.Transmission curves of the FORS OII +44?lter (solid)and the HST U 300(dashed).

VLT/ISAAC and HST/WFPC2optical images.Thus,we selected the HDFS/WFPC2?eld as our target ?eld.

There are 24galaxies with I 814≤25.0mag(AB)2and z ph ≥2.5in the ?eld.We set this lower limit of z ph ,taking into account the 2-σuncertainty of z ph for z ~3(σ≈0.08(1+z )noted in Labb′e et al.2003).Eight of them have z ph larger than 3.18.On the other hand,six out of 24have z sp ,but all of them are less than 3.18.We note that all the known z sp are smaller than the corresponding z ph .

An accurate redshift is essential to avoid contamina-tion from nonionizing photons.We need a redshift accu-racy of the order of 0.01.Since the accuracy of z ph is not su?cient,we performed spectroscopic observations with FORS2on VLT using the MXU mode.A full description of the observation will be published elsewhere (Iwata et al.in preparation).Here,we summarize the results brie?y.Because of the limitation of the slit-let con?guration,we were able to take spectra of only 15galaxies out of the above 24galaxies.Five out of the 15galaxies have known z sp and 7of them have z ph >3.18.The choice of galaxies was made with a priority given to more luminous galaxies and galaxies with z ph >3.18.Additionally,we took spectra of galaxies with z ph ≥2.5but I 814>25.0mag(AB),for which we could con?gure the slit-let.Among these galaxies,one has z sp previously measured.We ended up with obtaining 13z sp :seven of them are new mea-surements and the remaining six are con?rmations of the previous results.

Among the new redshifts,we got only one galaxy with a high enough redshift,z sp =3.275(HDFS 1825),in contrast to the expectation from photometric red-shifts.Indeed,for the 13galaxies with z sp ,we always ?nd

z sp

2.3.Imaging observations

The HDFS ?eld was observed through the OII +44narrow-band ?lter with FORS1and the TK2048EB4-1detector chip in service mode from 29June 2003to 28August 2003.The standard resolution collimator was adopted,giving a pixel scale of 0.′′2per pixel.The ?eld of view is 6.′8×6.′8and covers the whole area of the HDFS/WFPC2?eld.Each image was taken with a small dithering (typically 10′′)and a typical exposure time of 1,080sec.The seeing size of each image was 0.′′39–1.′′23,typically ~0.′′8.We secured 38images of the ?eld.The e?ective exposure time is 40,636sec (i.e.about 11h).Table 1shows a summary of the observations.

3.Data reduction and results 3.1.Final image

The image data reduction was carried out in a standard manner,using IRAF 3.The bias subtraction was made us-ing over-scanned regions.Normalized twilight sky frames in each observing night were used for ?at ?elding.We se-lected 25stars in the ?eld and used them to register the 38frames.After registration,the rms of residual shifts was 0.03pixel.These stars were also used for an airmass correction.We found a slope of magnitude dependence on airmass of ?0.45,and we corrected observed counts as

4Inoue et al.:Upper limit of Lyman continuum

escape

Fig.2.Close-up of sample galaxies through the OII+44?lter(VLT/FORS,this work),and the I814?lter (HST/WFPC2,Williams et al.,2000).The FOVs are20′′×20′′.For the object85,the image center is6′′shifted from the object position,because it is close to an edge of I814image.

it would have been observed at the zenith.The stability of the observing conditions is con?rmed by measuring the corrected counts of these stars;the rms errors in counts are less than0.05mag for19stars brighter than22mag(AB) through the OII+44?lter among the above25stars. Then,the IRAF task IMCOMBINE was used to sum the frames.We took averages of each pixel adopting a3-σclipping.FWHM of stellar objects in the?nal image is ~1′′.Fig.2shows the close-up images of the two sample galaxies through the OII+44?lter and through the I814?lter of HST/WFPC2.Neither galaxy seems to be seen through the OII+44?lter.

3.2.Photometry

Three standard stars,Feige110,G93-48,and LTT9491, were also observed through the same?lter.These frames were processed in the same way as the HDFS frames.The absolute AB magnitude of these stars were calculated from the spectral table provided on ESO web page.We found that the airmass dependence for the standard stars was ?0.58which is somewhat larger than that from stars in the HDFS frames.We derived the photometric zero point for the OII+44?lter at the zenith as22.98from the airmass slope of the standard stars.The zero point changes less than0.02mag if we adopt the airmass slope?0.45which we used for correction of the HDFS frames.

To reduce background?uctuations,we apply a Gaussian smoothing to the?nal image adapted to the ex-pected size of the sample galaxies through the OII+44?lter.The size through the HST/WFPC2B450?lter is a reasonable approximation because the central wavelength is close to that of the OII+44?lter and we are seeing the light from massive stars in both?lters.Diameters of

Inoue et al.:Upper limit of Lyman continuum escape5 Table2.Photometric properties of sample galaxies.

ID a851825

L int LC =exp(?τISM

LC

),(1)

where L int LC is the intrinsic LC luminosity density(per Hz)

of a galaxy,L out

LC

is the LC luminosity density just outside

of the galaxy(not the observed one,see below),andτISM

LC

is the opacity of the interstellar medium(ISM)for LC

photons in the galaxy.The other is

f esc,rel≡f esc L out UV

(F UV/F LC)obs

exp(τIGM

LC

),(3)

where we have replaced the observed luminosity density

ratio into the observed?ux density ratio.Hence,the

relative escape fraction can be estimated from the ob-

served UV-to-LC?ux density ratio if we know the intrinsic

UV-to-LC luminosity density ratio and the IGM opacity.

Moreover,the absolute escape fraction can be estimated

from the relative escape fraction via equation(2)if we

know the ISM opacity for nonionizing UV photons.

4.2.Intrinsic luminosity density ratios

The intrinsic UV-to-LC luminosity density ratio is still

very uncertain observationally.As noted by S01,we must

rely exclusively on models.Here we adopt the Starburst

99model(Leitherer et al.,1999).From this model,we

obtain(L1500/L900)int=1.5–5.5as shown in Fig.3,as-

suming a constant star formation rate,the Salpeter initial

mass function with the mass range of0.1–100M⊙,and

the metallicity of0.001–0.02(the solar value is0.02).The

luminosity density ratios mainly depend on the duration

since the onset of star formation;the ratio starts from a

small value,monotonically increases with time,and satu-

rates at a larger value after several108yrs.In this paper,

we adopt(L1500/L900)int=3.0according to the value

adopted by S01.4

6Inoue et al.:Upper limit of Lyman continuum escape Table3.Adopted intrinsic ratios of luminosity densities

relative to1500?A.

x(L1500/L x)int a

(?A)

Inoue et al.:Upper limit of Lyman continuum escape7 Table4.Summary of related observations and escape fractions.

Redshift range/method/redshift(F UV/F LC)obs aτIGM

LC f esc,rel aλUV,λLC b L UV c A UV d ref.e f esc a

galaxy name(%)(1029erg s?1Hz?1)(mag)(%) (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)

z~1

Broadband photometry

Cl J0023+0423:[LPO98a]022 1.1074>1870.53<3.050.967 1.33<0.91 CFRS03.1140 1.1818>3080.59<1.76 2.56......<1.7 CFRS10.1887 1.2370>1190.63<4.560.969......<4.5 CFRS10.0239 1.2919>2280.68<2.56 2.28......<2.5 CFRS10.1168 1.1592>1630.57<3.160.802......<3.1 LDSS210.288 1.108>1020.53<5.550.859......<5.5 HDF:iw410021353 1.221>67.80.62<10.040.513 2.64<0.91 CFRS14.0547 1.160>3480.57<1.84 1.55 2.24<0.24 CFRS14.0154 1.1583>1920.57<3.440.610 2.94<0.24 SSA22-16 1.36>1650.74<4.64 1.050.204<3.8 CFRS22.1153 1.3118>1250.54<5.04 1.00 1.64<1.1

5There is one more galaxy(HDFN:[FLY99]688)satisfying

the redshift criterion in the list of FS03,but it is detected

by Chandra as a X-ray source(Hornschemeier et al.,2001).

Hence,we remove it from our discussions because it may be an

AGN.

8Inoue et al.:Upper limit of Lyman continuum escape

relative escape fraction(f esc,rel,column5),using the in-trinsic luminosity density ratios(Sect.4.2)and the IGM opacity model(Sect.4.3,column5),which are tailored to the speci?c wavelength and the?lter bandpass(column6) for each individual galaxy.

5.1.1.z~3galaxies

The column3in the top of Table4shows that our two observed lower limits of F UV/F LC are comparable to those already obtained for galaxies at z~3.G02have reached constraints about two times better than ours,because their two objects are more than two times intrinsically brighter.Our objects,as those of S01,are comparable in luminosity to the L?of z~3LBGs(see column7; L?(z=3)~1×1029erg s?1Hz?1;Steidel et al.,1999; Adelberger&Steidel,2000).

In terms of relative escape fraction(column5),we add one more object(HDFS85)to the two galaxies of G02that have been reported with a relative escape fraction lower than the detection of S01.Because of the small sample size,these lower limits remain consistent with the rela-tive escape fraction of S01.Although we have applied a mean IGM opacity for simplicity,a line of sight with larger than average opacity cannot be ruled out for an individual galaxy(not to speak of an unusual object as the escape is probably a random phenomenon).

The broad-band U300photometry in the HDFN reaches similar lower limits on F UV/F LC(it would have reached slightly better values at the same luminosity level as ours).This,however,does not result in interesting con-straints on the relative escape fraction because of the IGM opacity.The IGM opacity through the U300?lter,with an e?ective wavelength of700?A in the source rest-frame,is much larger than those at wavelengths closer to the rest 900?A(column4).Since meaningful constraints on the rel-ative escape fraction are not reached,this sample will be removed from discussions in terms of the absolute escape fraction presented below.

The top of Table4is also interesting for a comparison of methods of observations and a validation of future ap-proaches.As expected,the narrow-band photometry can provide better constraints than spectroscopy.The better constraints of G02are actually due to the high luminos-ity of the objects.If our sample had a similar luminosity to the galaxies of G02,say,L=4×1029erg s?1Hz?1, we would have obtained F UV/F LC>~40(3-σlevel).The broad-band photometry is disquali?ed by the IGM opac-ity contribution(or requires the help of models that lead to less direct constraints).The narrow-band photometry can provide,even for a single L?LBG,a lower limit on F UV/F LC comparable with that measured in the compos-ite spectrum of29galaxies by S01.Stacking a signi?cant number of galaxies observed through a narrow-band?l-ter will be able to go much deeper.We can also average the IGM opacity against any unusual line of sight in the stacking process.Such an approach would allow a signif-icant comparison with the result of S01and reveal which fraction of high-z galaxies have high relative LC escape fraction.

5.1.2.z~1galaxies

Thanks to the high sensitivity of the HST/STIS,M03have obtained very good lower limits on the?ux density ratio of11galaxies at z~1,F UV/F LC>70–350at3-σcon-?dence level(column3in the middle of Table4).With the correction for the average IGM opacity described in section4.3,these ratios are converted to upper limits on the relative escape fraction of2–10%(column5).The lu-minosities of this sample are similar to L?of z~3LBGs (column7).

The average IGM opacity(column4)is much smaller than those at high redshift,but not completely negligible as assumed by M03,if we consider the Lyman limit sys-tems(LLSs)which dominate the IGM opacity for z~1 galaxies.The rarity of LLSs favors a statistical treatment rather than the average opacity adopted above.Based on the number distribution function of the IGM clouds as-sumed here(see Appendix),the expected number of LLSs within the wavelength range observed by M03(1300?A <~λ

obs

<~1900?A)is about0.3.Roughly speaking,for one-third of the objects of M03,the LLSs would loosen the constraints obtained under the assumption of no IGM opacity.In this sense,the number of galaxies in M03is large enough to conclude a very small relative escape frac-tion for their objects.

5.1.3.Nearby galaxies

Although the upper limits on the LC from nearby galax-ies have been estimated from their Hα?uxes directly in terms of absolute escape fraction(Leitherer et al.,1995; Hurwitz et al.,1997;Deharveng et al.,2001),it is pos-sible to evaluate the observed lower limits of F UV/F LC for comparison with higher z objects(the bottom part of Table4;Table1in Deharveng et al.,2001).Except for Mrk54,these limits,corrected for the foreground absorp-tion by the Galactic HI and H2gas,are not better than those obtained at high-z(column3).The low luminos-ity of the sample galaxies is one of the causes(column 7).Nevertheless,moderate upper limits are obtained for the relative escape fraction,<25–40%(3-σcon?dence level;column5),because no correction for the IGM opac-ity is necessary.For Mrk54,whose luminosity is similar to those of our sample(column7),the observed lower limit of Deharveng et al.(2001)translates into an upper limit on the relative escape fraction of3%comparable to those for z~1galaxies of M03(column5).

5.2.Absolute escape fraction

As discussed above and shown by equation(2),estimat-ing the absolute escape fraction from the relative escape

Inoue et al.:Upper limit of Lyman continuum escape9 fraction requires an evaluation of the dust attenuation

within each galaxy which is often di?cult and uncertain

(e.g.,Buat et al.,2002;Pettini et al.,1998;Meurer et al.,

1999).Although the infrared to UV?ux ratio is a

good estimator of the UV attenuation(Buat et al.,1999;

Gordon et al.,2000),the infrared?uxes for high-z galaxies

are not available yet.Here,we adopt a calibration between

the nonionizing UV slope and the UV attenuation pro-

posed by Meurer et al.(1999)for simplicity.However,we

should keep in mind that the calibration depends on the

type of galaxies,starburst or not(Bell,2002;Kong et al.,

2004).

The UV slope of the galaxies listed in Table4have

been searched in the literature,or,if not available,esti-

mated from broad-band measurements with the assump-

tion of a power-low spectrum(fλ∝λβ)6(references in

column9of Table4).This was not possible for some

galaxies of M03because their colors in the rest-frame

λ<3000?A are not available.For the composite spec-

trum of S01,we estimated the UV attenuation from the

reported mean E(B?V)via the Calzetti’s attenuation

law(Calzetti et al.,2000).The UV slope of the composite

spectrum shown in Fig.1of S01is consistent with the slope

corresponding to the estimated attenuation.We estimated

UV slopes of our two galaxies from their broad-band colors

although we have UV spectra of our two galaxies because

the data quality is not good.7

Since the calibration gives the attenuation at the rest-

frame1600?A,we convert it into the attenuation at the

appropriate UV wavelength by the Calzetti’s attenuation

law(Calzetti et al.,2000)if the UV wavelength is di?erent

from1600?A(column8).We note here that the uncertainty

resulting from those on the UV slope and colors is very

large;for example,the uncertainty of about0.05mag in

V606?I814for our two galaxies translates into?A UV~

2?β~6?(V606?I814)~0.3mag(see Meurer et al.,

1999).

For galaxies at z~3,we?nd that(1)the absolute

escape fraction from the detection by S01is60±13%

(1-σobservational uncertainty),(2)the absolute escape

fraction of the two brightest LBGs observed by G02is

less than5%(3-σ),(3)the absolute escape fraction of L?

LBGs observed by us is less than20–40%(3-σ).

For z~1galaxies,we?nd very small upper limits on

the absolute escape fraction,typically,less than a few per-

cent(3-σ).Since small upper limits were obtained even for

the relative escape fraction,the conclusion of very small

absolute escape fractions for the observed galaxies seems

robust against the uncertainty of estimating the dust at-

tenuation.

10Inoue et al.:Upper limit of Lyman continuum escape

opacity.Stacking a signi?cant number of deep narrow-band images of drop-out galaxies has,therefore,the potential to con?rm or not the high relative escape fraction reported by Steidel et al.(2001).In addition to increasing sensitivity,such a method would average the IGM opacity and the randomness of the LC escape. Acknowledgements.We thank Tsutomu T.Takeuchi for a lot of valuable comments,Matthew A.Bershady for kindly providing us with his opacity model as a machine-readable form,Alberto Fern′a ndez-Soto for helpful discussions,and ESO support astronomers for their cooperation during the phase 2submission and observations.AKI also thanks Hiroyuki Hirashita,Masayuki Akiyama,Hideyuki Kamaya,and Shu-ichiro Inutsuka for their continuous encouragements.In the middle of this work,AKI was invited to the Laroratoire d’Astrophysique de Marseille and?nancially supported by the Observatoire Astronomique de Marseille-Provence.AKI is also supported by the JSPS Postdoctoral Fellowships for Research Abroad.

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Steidel, C. C.,Adelberger,K.L.,Giavalisco,M., Dickinson,M.,&Pettini,M.1999,ApJ,519,1 Steidel,C.C.,Pettini,M.,&Adelberger,K.L.2001,ApJ, 546,665(S01)

Stengler-Larrea,E.A.,et al.1995,ApJ,444,64 Weymann,et al.1998,ApJ,506,1

Whittet,D.C.B.2003,Dust in the galactic environment, 2nd ed.(Bristol:IOP)

Wiese,W.L.,Smith,M.W.,&Glennon,B.M.1966, Atomic Transition Probabilities,Vol.1(NSRDS-NBS 4;Washington:GPO)

Williams,R.E.,et al.2000,AJ120,2735

Zheng,W.et al.2004,ApJ,605,631

Zuo,L.,&Phinney,E.S.1993,ApJ,418,28

Inoue et al.:Upper limit of Lyman continuum escape 11

Appendix A:A mean IGM opacity model

In this appendix,we ?rst show that the number density distribution function of the Lyman limit systems (LLSs)reasonably agrees with an extension of the distribution function of the Lyman αforest,in contrast to previous works.That is,the intergalactic clouds may be described by a continuous distribution from low-to high-density through any redshift.Second,we present an analytic approximation of a mean opacity of the intergalactic medium (IGM)based on the distribution function.

A mean IGM opacity at an observed wavelength λobs against a source with z =z S can be expressed as (e.g.,M?ller &Jakobsen,1990;Madau,1995)

τIGM

λobs (z S ) =

z S 0

dz N HI ,up

N HI ,low

dN HI ?2N ?z?N HI

=f (N HI )g (z ),(A.2)

where f (N HI )∝N ?β

HI with the normalization as N HI ,up

N HI ,low

f (N HI )dN HI =1and

g (z )=A (1+z )γ.We note here that the normalization A means the total number of the IGM cloud per unit redshift interval and is a function of N HI ,low and N HI ,up .

Observationally,the power-law index βmay be regarded as a constant equal to about 1.5for a wide range of column densities from log N HI /cm ?2=12.5to 21.5,although it seems to depend on redshift and column density in detail (Sargent et al.,1989;Petitjean et al.,1993;Kim et al.,2002;P′e roux et al.,2003).For simplicity,we assume a single power-law index β=1.5for all redshifts and column densities.

For the cloud number evolution with redshift,Madau (1995)adopted two di?erent evolutionary indices (γ)for the

Lyman αforest (N HI <~1017cm ?2)and for the LLSs (N HI >~1017cm ?2

),based on observations by Murdoch et al.(1986)and Sargent et al.(1989).However,the same index γfor these populations is compatible with recent ob-servations as shown in Fig.A.1.The LLS number evolution is reproduced from P′e roux et al.(2003)in this ?gure as the ?lled square points with error bars.The solid line is the number evolution of the Lyman αforest reported by Kim et al.(2002)and Weymann et al.(1998)multiplied by the reduction factor due to the lowest column den-sity considered;Kim et al.(2002)deal with Lyman αforest with log N HI /cm ?2=13.644–17,whereas P′e roux et al.

(2003)deal with the clouds with a column density larger than 1.6×1017cm ?2

,so that the multiplicative factor is (4.4×1013/1.6×1017)β?1≈0.017when β=1.5.There is a systematic disagreement along the vertical axis for high-z points between the solid line and the data,but the evolutionary slopes are consistent as noted by P′e roux et al.(2003).The high-z data are reproduced by the dashed line whose reduction factor is 0.01.On the other hand,the LLS number evolution reported by Sargent et al.(1989)and adopted by Madau (1995)is shown as the dotted line in Fig.A1and cannot reproduce the data points of P′e roux et al.(2003).Although the number evolution suggested by Stengler-Larrea et al.(1995)shows a better ?t (dash-dotted line),in this paper,we assume the case of the solid line.This means that we assume the same redshift evolution of the cloud number density over the entire column density range with β=1.5.

Under a cloud distribution function with a single power-law index β(1<β<2)and the same evolutionary index γfor all range of the column density,we take a set of limiting column densities as σH N HI ,low ?1and σH N HI ,up ?1,for example,N HI ,low =1012cm ?2and N HI ,up =1022cm ?2.In this case,equation (A.1)can be approximated as

τIGM

λobs

(z S ) ≈ z S

Γ(2?β)A N β?1HI ,low (1+z )γσH (λobs /1+z )β?1dz ,(A.3)where Γ(2?β)is the usual Gamma function (Zuo &Phinney,1993).The factor,A N β?1

HI ,low can be estimated from the observed number of clouds for a limited range of the column density with the power-law distribution.If the number of clouds with a column density between N l and N u (N HI ,low ≤N l

have A N β?1HI ,low ≈A ′N β?1

l

when N HI ,up /N HI ,low ?1,N u /N HI ,low ?1,and β>1.According to Kim et al.(2002)and Weymann et al.(1998),we adopt (A ′,γ)=(6,2.5)for z >1.1and (34,0.2)for z ≤1.1against log N HI /cm ?2=13.64–17(i.e.N l =4.4×1013cm ?2).

We will present an analytic approximation of equation (A.3),although we can integrate it numerically with a detailed function of the hydrogen cross section,σH .We adopt an approximated form of the cross section for the analytical formula.The point is that the cross section of the i -th line,σi (λ),can be neglected for a wavelength λout of a small range of |λ?λi |<~b/c ,where λi is the central wavelength of the line,b is the Doppler parameter,and c is

12Inoue et al.:Upper limit of Lyman continuum escape

N L L S (z )

1+z

Fig.A.1.Number density evolution of the Lyman limit systems (LLSs;log N HI /cm ?2=17.2–20)in a unit redshift interval along a line of sight.Data points with error-bars are taken from P′e roux et al.(2003).The solid line is the

number evolution expected from that of the Lyman αforest (log N HI /cm ?2

=13.64–17)reported by Kim et al.(2002)and Weymann et al.(1998)with a single power-law distribution of the column density;the number of LLSs is that of Lyman αforest multiplied by (4.4×1013/1.6×1017)β?1≈0.017when β=1.5.The dashed line is the same as the solid line but the multiple factor is 0.01.The dotted line is the number evolution of LLSs reported by Sargent et al.(1989),and the dash-dotted line is that reported by Stengler-Larrea et al.(1995).

the speed of light.Besides,the cross section for LC,σLC (λ),is zero when λ>λL =912?A .Thus,we can approximate σH (λ)β?1

(=[σLC (λ)+ i σi (λ)]

β?1)to σLC (λ)β?1+ i σi (λ)β?1,because only one term has meaningful value for a speci?c wavelength λ.

Adopting this approximation,we can reduce equation (A.3)to

τIGM λobs (z S )

≈τLC λobs +

i

τi λobs

,(A.4)where

τLC λobs

=

Γ(2?β)(σL N HI ,low )

β?1

λobs

c

λ

obs

8

We approximately take into account the Voigt pro?le by the following equation;φ(x )≈exp(?x 2)+a/

Inoue et al.:Upper limit of Lyman continuum escape 13

0.01

0.1

1

10

1000

20003000400050006000

I G M o p t i c a l d e p t h

observed wavelength [A]

z S =1z S =2z S =3z S =4

Fig.A.2.Examples of the IGM optical depth calculated by an analytic approximation presented as equations (A.4–6).The dotted curve is the model “MC-Kim”by Bershady et al.(1999).

All calculations include up to 40-th line of Lyman series whose central cross sections are calculated by the data taken from Wiese et al.(1966).

Fig.A.2shows the mean IGM opacities for several source redshifts calculated by equations (A.4–6)with the distribution function based on Kim et al.(2002)and (δ,b )=(2.6,30km s ?1).Since Kim’s observations are made against Lyman αforest below z ~4,we have shown cases up to z S =4.As a comparison with a previous opacity model,we also plot the result by Bershady et al.(1999)(the case of “MC-Kim”)as the dotted curve in the ?gure.Since they adopted the LLS number evolution of Sargent et al.(1989)as done by Madau (1995),there are some discrepancies between ours and theirs;our larger (smaller)optical depth at around the observed 3000(1500)?A than Bershady et al.(1999)is caused by our larger (smaller)number of LLSs at z >~2(<~2)than Sargent et al.(1989)as shown in Fig.A.1.However,the quantitative agreement is reasonably good.

As another test,we compare our optical depth with that measured by Steidel et al.(2001).From a comparison between two composite spectra of galaxies and QSOs at z ?3.4and 3.3,respectively,Steidel et al.(2001)have found a mean IGM optical depth of 1.35for the rest-frame 900?A ,whereas our model gives 1.36for the wavelength and z =3.4source.We have found an excellent agreement with each other.

The way常见用法

The way 的用法 Ⅰ常见用法: 1)the way+ that 2)the way + in which(最为正式的用法) 3)the way + 省略(最为自然的用法) 举例:I like the way in which he talks. I like the way that he talks. I like the way he talks. Ⅱ习惯用法: 在当代美国英语中,the way用作为副词的对格,“the way+ 从句”实际上相当于一个状语从句来修饰整个句子。 1)The way =as I am talking to you just the way I’d talk to my own child. He did not do it the way his friends did. Most fruits are naturally sweet and we can eat them just the way they are—all we have to do is to clean and peel them. 2)The way= according to the way/ judging from the way The way you answer the question, you are an excellent student. The way most people look at you, you’d think trash man is a monster. 3)The way =how/ how much No one can imagine the way he missed her. 4)The way =because

The way的用法及其含义(二)

The way的用法及其含义(二) 二、the way在句中的语法作用 the way在句中可以作主语、宾语或表语: 1.作主语 The way you are doing it is completely crazy.你这个干法简直发疯。 The way she puts on that accent really irritates me. 她故意操那种口音的样子实在令我恼火。The way she behaved towards him was utterly ruthless. 她对待他真是无情至极。 Words are important, but the way a person stands, folds his or her arms or moves his or her hands can also give us information about his or her feelings. 言语固然重要,但人的站姿,抱臂的方式和手势也回告诉我们他(她)的情感。 2.作宾语 I hate the way she stared at me.我讨厌她盯我看的样子。 We like the way that her hair hangs down.我们喜欢她的头发笔直地垂下来。 You could tell she was foreign by the way she was dressed. 从她的穿著就可以看出她是外国人。 She could not hide her amusement at the way he was dancing. 她见他跳舞的姿势,忍俊不禁。 3.作表语 This is the way the accident happened.这就是事故如何发生的。 Believe it or not, that's the way it is. 信不信由你, 反正事情就是这样。 That's the way I look at it, too. 我也是这么想。 That was the way minority nationalities were treated in old China. 那就是少数民族在旧中

(完整版)the的用法

定冠词the的用法: 定冠词the与指示代词this ,that同源,有“那(这)个”的意思,但较弱,可以和一个名词连用,来表示某个或某些特定的人或东西. (1)特指双方都明白的人或物 Take the medicine.把药吃了. (2)上文提到过的人或事 He bought a house.他买了幢房子. I've been to the house.我去过那幢房子. (3)指世界上独一无二的事物 the sun ,the sky ,the moon, the earth (4)单数名词连用表示一类事物 the dollar 美元 the fox 狐狸 或与形容词或分词连用,表示一类人 the rich 富人 the living 生者 (5)用在序数词和形容词最高级,及形容词等前面 Where do you live?你住在哪? I live on the second floor.我住在二楼. That's the very thing I've been looking for.那正是我要找的东西. (6)与复数名词连用,指整个群体 They are the teachers of this school.(指全体教师) They are teachers of this school.(指部分教师) (7)表示所有,相当于物主代词,用在表示身体部位的名词前 She caught me by the arm.她抓住了我的手臂. (8)用在某些有普通名词构成的国家名称,机关团体,阶级等专有名词前 the People's Republic of China 中华人民共和国 the United States 美国 (9)用在表示乐器的名词前 She plays the piano.她会弹钢琴. (10)用在姓氏的复数名词之前,表示一家人 the Greens 格林一家人(或格林夫妇) (11)用在惯用语中 in the day, in the morning... the day before yesterday, the next morning... in the sky... in the dark... in the end... on the whole, by the way...

“the way+从句”结构的意义及用法

“theway+从句”结构的意义及用法 首先让我们来看下面这个句子: Read the followingpassageand talkabout it wi th your classmates.Try totell whatyou think of Tom and ofthe way the childrentreated him. 在这个句子中,the way是先行词,后面是省略了关系副词that或in which的定语从句。 下面我们将叙述“the way+从句”结构的用法。 1.the way之后,引导定语从句的关系词是that而不是how,因此,<<现代英语惯用法词典>>中所给出的下面两个句子是错误的:This is thewayhowithappened. This is the way how he always treats me. 2.在正式语体中,that可被in which所代替;在非正式语体中,that则往往省略。由此我们得到theway后接定语从句时的三种模式:1) the way+that-从句2)the way +in which-从句3) the way +从句 例如:The way(in which ,that) thesecomrade slookatproblems is wrong.这些同志看问题的方法

不对。 Theway(that ,in which)you’re doingit is comple tely crazy.你这么个干法,简直发疯。 Weadmired him for theway inwhich he facesdifficulties. Wallace and Darwingreed on the way inwhi ch different forms of life had begun.华莱士和达尔文对不同类型的生物是如何起源的持相同的观点。 This is the way(that) hedid it. I likedthe way(that) sheorganized the meeting. 3.theway(that)有时可以与how(作“如何”解)通用。例如: That’s the way(that) shespoke. = That’s how shespoke.

way 用法

表示“方式”、“方法”,注意以下用法: 1.表示用某种方法或按某种方式,通常用介词in(此介词有时可省略)。如: Do it (in) your own way. 按你自己的方法做吧。 Please do not talk (in) that way. 请不要那样说。 2.表示做某事的方式或方法,其后可接不定式或of doing sth。 如: It’s the best way of studying [to study] English. 这是学习英语的最好方法。 There are different ways to do [of doing] it. 做这事有不同的办法。 3.其后通常可直接跟一个定语从句(不用任何引导词),也可跟由that 或in which 引导的定语从句,但是其后的从句不能由how 来引导。如: 我不喜欢他说话的态度。 正:I don’t like the way he spoke. 正:I don’t like the way that he spoke. 正:I don’t like the way in which he spoke. 误:I don’t like the way how he spoke. 4.注意以下各句the way 的用法: That’s the way (=how) he spoke. 那就是他说话的方式。 Nobody else loves you the way(=as) I do. 没有人像我这样爱你。 The way (=According as) you are studying now, you won’tmake much progress. 根据你现在学习情况来看,你不会有多大的进步。 2007年陕西省高考英语中有这样一道单项填空题: ——I think he is taking an active part insocial work. ——I agree with you_____. A、in a way B、on the way C、by the way D、in the way 此题答案选A。要想弄清为什么选A,而不选其他几项,则要弄清选项中含way的四个短语的不同意义和用法,下面我们就对此作一归纳和小结。 一、in a way的用法 表示:在一定程度上,从某方面说。如: In a way he was right.在某种程度上他是对的。注:in a way也可说成in one way。 二、on the way的用法 1、表示:即将来(去),就要来(去)。如: Spring is on the way.春天快到了。 I'd better be on my way soon.我最好还是快点儿走。 Radio forecasts said a sixth-grade wind was on the way.无线电预报说将有六级大风。 2、表示:在路上,在行进中。如: He stopped for breakfast on the way.他中途停下吃早点。 We had some good laughs on the way.我们在路上好好笑了一阵子。 3、表示:(婴儿)尚未出生。如: She has two children with another one on the way.她有两个孩子,现在还怀着一个。 She's got five children,and another one is on the way.她已经有5个孩子了,另一个又快生了。 三、by the way的用法

The way的用法及其含义(一)

The way的用法及其含义(一) 有这样一个句子:In 1770 the room was completed the way she wanted. 1770年,这间琥珀屋按照她的要求完成了。 the way在句中的语法作用是什么?其意义如何?在阅读时,学生经常会碰到一些含有the way 的句子,如:No one knows the way he invented the machine. He did not do the experiment the way his teacher told him.等等。他们对the way 的用法和含义比较模糊。在这几个句子中,the way之后的部分都是定语从句。第一句的意思是,“没人知道他是怎样发明这台机器的。”the way的意思相当于how;第二句的意思是,“他没有按照老师说的那样做实验。”the way 的意思相当于as。在In 1770 the room was completed the way she wanted.这句话中,the way也是as的含义。随着现代英语的发展,the way的用法已越来越普遍了。下面,我们从the way的语法作用和意义等方面做一考查和分析: 一、the way作先行词,后接定语从句 以下3种表达都是正确的。例如:“我喜欢她笑的样子。” 1. the way+ in which +从句 I like the way in which she smiles. 2. the way+ that +从句 I like the way that she smiles. 3. the way + 从句(省略了in which或that) I like the way she smiles. 又如:“火灾如何发生的,有好几种说法。” 1. There were several theories about the way in which the fire started. 2. There were several theories about the way that the fire started.

way 的用法

way 的用法 【语境展示】 1. Now I’ll show you how to do the experiment in a different way. 下面我来演示如何用一种不同的方法做这个实验。 2. The teacher had a strange way to make his classes lively and interesting. 这位老师有种奇怪的办法让他的课生动有趣。 3. Can you tell me the best way of working out this problem? 你能告诉我算出这道题的最好方法吗? 4. I don’t know the way (that / in which) he helped her out. 我不知道他用什么方法帮助她摆脱困境的。 5. The way (that / which) he talked about to solve the problem was difficult to understand. 他所谈到的解决这个问题的方法难以理解。 6. I don’t like the way that / which is being widely used for saving water. 我不喜欢这种正在被广泛使用的节水方法。 7. They did not do it the way we do now. 他们以前的做法和我们现在不一样。 【归纳总结】 ●way作“方法,方式”讲时,如表示“以……方式”,前面常加介词in。如例1; ●way作“方法,方式”讲时,其后可接不定式to do sth.,也可接of doing sth. 作定语,表示做某事的方法。如例2,例3;

the-way-的用法讲解学习

t h e-w a y-的用法

The way 的用法 "the way+从句"结构在英语教科书中出现的频率较高, the way 是先行词, 其后是定语从句.它有三种表达形式:1) the way+that 2)the way+ in which 3)the way + 从句(省略了that或in which),在通常情况下, 用in which 引导的定语从句最为正式,用that的次之,而省略了关系代词that 或 in which 的, 反而显得更自然,最为常用.如下面三句话所示,其意义相同. I like the way in which he talks. I like the way that he talks. I like the way he talks. 一.在当代美国英语中,the way用作为副词的对格,"the way+从句"实际上相当于一个状语从句来修饰全句. the way=as 1)I'm talking to you just the way I'd talk to a boy of my own. 我和你说话就象和自己孩子说话一样. 2)He did not do it the way his friend did. 他没有象他朋友那样去做此事. 3)Most fruits are naturally sweet and we can eat them just the way they are ----all we have to do is clean or peel them . 大部分水果天然甜润,可以直接食用,我们只需要把他们清洗一下或去皮.

way的用法总结大全

way的用法总结大全 way的用法你知道多少,今天给大家带来way的用法,希望能够帮助到大家,下面就和大家分享,来欣赏一下吧。 way的用法总结大全 way的意思 n. 道路,方法,方向,某方面 adv. 远远地,大大地 way用法 way可以用作名词 way的基本意思是“路,道,街,径”,一般用来指具体的“路,道路”,也可指通向某地的“方向”“路线”或做某事所采用的手段,即“方式,方法”。way还可指“习俗,作风”“距离”“附近,周围”“某方面”等。 way作“方法,方式,手段”解时,前面常加介词in。如果way前有this, that等限定词,介词可省略,但如果放在句首,介词则不可省略。

way作“方式,方法”解时,其后可接of v -ing或to- v 作定语,也可接定语从句,引导从句的关系代词或关系副词常可省略。 way用作名词的用法例句 I am on my way to the grocery store.我正在去杂货店的路上。 We lost the way in the dark.我们在黑夜中迷路了。 He asked me the way to London.他问我去伦敦的路。 way可以用作副词 way用作副词时意思是“远远地,大大地”,通常指在程度或距离上有一定的差距。 way back表示“很久以前”。 way用作副词的用法例句 It seems like Im always way too busy with work.我工作总是太忙了。 His ideas were way ahead of his time.他的思想远远超越了他那个时代。 She finished the race way ahead of the other runners.她第一个跑到终点,远远领先于其他选手。 way用法例句

the_way的用法大全教案资料

t h e_w a y的用法大全

The way 在the way+从句中, the way 是先行词, 其后是定语从句.它有三种表达形式:1) the way+that 2)the way+ in which 3)the way + 从句(省略了that或in which),在通常情况下, 用in which 引导的定语从句最为正式,用that的次之,而省略了关系代词that 或 in which 的, 反而显得更自然,最为常用.如下面三句话所示,其意义相同. I like the way in which he talks. I like the way that he talks. I like the way he talks. 如果怕弄混淆,下面的可以不看了 另外,在当代美国英语中,the way用作为副词的对格,"the way+从句"实际上相当于一个状语从句来修饰全句. the way=as 1)I'm talking to you just the way I'd talk to a boy of my own. 我和你说话就象和自己孩子说话一样. 2)He did not do it the way his friend did. 他没有象他朋友那样去做此事. 3)Most fruits are naturally sweet and we can eat them just the way they are ----all we have to do is clean or peel them . 大部分水果天然甜润,可以直接食用,我们只需要把他们清洗一下或去皮. the way=according to the way/judging from the way 4)The way you answer the qquestions, you must be an excellent student. 从你回答就知道,你是一个优秀的学生. 5)The way most people look at you, you'd think a trashman was a monster. 从大多数人看你的目光中,你就知道垃圾工在他们眼里是怪物. the way=how/how much 6)I know where you are from by the way you pronounce my name. 从你叫我名字的音调中,我知道你哪里人. 7)No one can imaine the way he misses her. 人们很想想象他是多么想念她. the way=because 8) No wonder that girls looks down upon me, the way you encourage her. 难怪那姑娘看不起我, 原来是你怂恿的

the way 的用法

The way 的用法 "the way+从句"结构在英语教科书中出现的频率较高, the way 是先行词, 其后是定语从句.它有三种表达形式:1) the way+that 2)the way+ in which 3)the way + 从句(省略了that或in which),在通常情况下, 用in which 引导的定语从句最为正式,用that的次之,而省略了关系代词that 或in which 的, 反而显得更自然,最为常用.如下面三句话所示,其意义相同. I like the way in which he talks. I like the way that he talks. I like the way he talks. 一.在当代美国英语中,the way用作为副词的对格,"the way+从句"实际上相当于一个状语从句来修饰全句. the way=as 1)I'm talking to you just the way I'd talk to a boy of my own. 我和你说话就象和自己孩子说话一样. 2)He did not do it the way his friend did. 他没有象他朋友那样去做此事. 3)Most fruits are naturally sweet and we can eat them just the way they are ----all we have to do is clean or peel them . 大部分水果天然甜润,可以直接食用,我们只需要把他们清洗一下或去皮.

the way=according to the way/judging from the way 4)The way you answer the qquestions, you must be an excellent student. 从你回答就知道,你是一个优秀的学生. 5)The way most people look at you, you'd think a trashman was a monster. 从大多数人看你的目光中,你就知道垃圾工在他们眼里是怪物. the way=how/how much 6)I know where you are from by the way you pronounce my name. 从你叫我名字的音调中,我知道你哪里人. 7)No one can imaine the way he misses her. 人们很想想象他是多么想念她. the way=because 8) No wonder that girls looks down upon me, the way you encourage her. 难怪那姑娘看不起我, 原来是你怂恿的 the way =while/when(表示对比) 9)From that day on, they walked into the classroom carrying defeat on their shoulders the way other students carried textbooks under their arms. 从那天起,其他同学是夹着书本来上课,而他们却带着"失败"的思想负担来上课.

The way的用法及其含义(三)

The way的用法及其含义(三) 三、the way的语义 1. the way=as(像) Please do it the way I’ve told you.请按照我告诉你的那样做。 I'm talking to you just the way I'd talk to a boy of my own.我和你说话就像和自己孩子说话一样。 Plant need water the way they need sun light. 植物需要水就像它们需要阳光一样。 2. the way=how(怎样,多么) No one can imagine the way he misses her.没人能够想象出他是多么想念她! I want to find out the way a volcano has formed.我想弄清楚火山是怎样形成的。 He was filled with anger at the way he had been treated.他因遭受如此待遇而怒火满腔。That’s the way she speaks.她就是那样讲话的。 3. the way=according as (根据) The way you answer the questions, you must be an excellent student.从你回答问题来看,你一定是名优秀的学生。 The way most people look at you, you'd think a trash man was a monster.从大多数人看你的目光中,你就知道垃圾工在他们眼里是怪物。 The way I look at it, it’s not what you do that matters so much.依我看,重要的并不是你做什么。 I might have been his son the way he talked.根据他说话的样子,好像我是他的儿子一样。One would think these men owned the earth the way they behave.他们这样行动,人家竟会以为他们是地球的主人。

way的用法

一.Way:“方式”、“方法” 1.表示用某种方法或按某种方式 Do it (in) your own way. Please do not talk (in) that way. 2.表示做某事的方式或方法 It’s the best way of studying [to study] English.。 There are different ways to do [of doing] it. 3.其后通常可直接跟一个定语从句(不用任何引导词),也可跟由that 或in which 引导的定语从句 正:I don’t like the way he spoke. I don’t like the way that he spoke. I don’t like the way in which he spoke.误:I don’t like the way how he spoke. 4. the way 的从句 That’s the way (=how) he spoke. I know where you are from by the way you pronounce my name. That was the way minority nationalities were treated in old China. Nobody else loves you the way(=as) I do. He did not do it the way his friend did. 二.固定搭配 1. In a/one way:In a way he was right. 2. In the way /get in one’s way I'm afraid your car is in the way, If you are not going to help,at least don't get in the way. You'll have to move-you're in my way. 3. in no way Theory can in no way be separated from practice. 4. On the way (to……) Let’s wait a few moments. He is on the way Spring is on the way. Radio forecasts said a sixth-grade wind was on the way. She has two children with another one on the way. 5. By the way By the way,do you know where Mary lives? 6. By way of Learn English by way of watching US TV series. 8. under way 1. Elbow one’s way He elbowed his way to the front of the queue. 2. shoulder one’s way 3. feel one‘s way 摸索着向前走;We couldn’t see anything in the cave, so we had to feel our way out 4. fight/force one’s way 突破。。。而前进The surrounded soldiers fought their way out. 5.. push/thrust one‘s way(在人群中)挤出一条路He pushed his way through the crowd. 6. wind one’s way 蜿蜒前进 7. lead the way 带路,领路;示范 8. lose one‘s way 迷失方向 9. clear the way 排除障碍,开路迷路 10. make one’s way 前进,行进The team slowly made their way through the jungle.

the way的用法大全

在the way+从句中, the way 是先行词, 其后是定语从句.它有三种表达形式:1) the way+that 2)the way+ in which 3)the way + 从句(省略了that或in which),在通常情况下, 用in which 引导的定语从句最为正式,用that的次之,而省略了关系代词that 或in which 的, 反而显得更自然,最为常用.如下面三句话所示,其意义相同. I like the way in which he talks. I like the way that he talks. I like the way he talks. 如果怕弄混淆,下面的可以不看了 另外,在当代美国英语中,the way用作为副词的对格,"the way+从句"实际上相当于一个状语从句来修饰全句. the way=as 1)I'm talking to you just the way I'd talk to a boy of my own. 我和你说话就象和自己孩子说话一样. 2)He did not do it the way his friend did. 他没有象他朋友那样去做此事. 3)Most fruits are naturally sweet and we can eat them just the way they are ----all we have to do is clean or peel them . 大部分水果天然甜润,可以直接食用,我们只需要把他们清洗一下或去皮. the way=according to the way/judging from the way 4)The way you answer the qquestions, you must be an excellent student. 从你回答就知道,你是一个优秀的学生. 5)The way most people look at you, you'd think a trashman was a monster. 从大多数人看你的目光中,你就知道垃圾工在他们眼里是怪物. the way=how/how much 6)I know where you are from by the way you pronounce my name. 从你叫我名字的音调中,我知道你哪里人. 7)No one can imaine the way he misses her. 人们很想想象他是多么想念她. the way=because 8) No wonder that girls looks down upon me, the way you encourage her. 难怪那姑娘看不起我, 原来是你怂恿的 the way =while/when(表示对比) 9)From that day on, they walked into the classroom carrying defeat on their shoulders the way other students carried textbooks under their arms.

“the-way+从句”结构的意义及用法知识讲解

“the way+从句”结构的意义及用法 首先让我们来看下面这个句子: Read the following passage and talk about it with your classmates. Try to tell what you think of Tom and of the way the children treated him. 在这个句子中,the way是先行词,后面是省略了关系副词that 或in which的定语从句。 下面我们将叙述“the way+从句”结构的用法。 1.the way之后,引导定语从句的关系词是that而不是how,因此,<<现代英语惯用法词典>>中所给出的下面两个句子是错误的:This is the way how it happened. This is the way how he always treats me. 2. 在正式语体中,that可被in which所代替;在非正式语体中,that则往往省略。由此我们得到the way后接定语从句时的三种模式:1) the way +that-从句2) the way +in which-从句3) the way +从句 例如:The way(in which ,that) these comrades look at problems is wrong.这些同志看问题的方法不对。

The way(that ,in which)you’re doing it is completely crazy.你这么个干法,简直发疯。 We admired him for the way in which he faces difficulties. Wallace and Darwin greed on the way in which different forms of life had begun.华莱士和达尔文对不同类型的生物是如何起源的持相同的观点。 This is the way (that) he did it. I liked the way (that) she organized the meeting. 3.the way(that)有时可以与how(作“如何”解)通用。例如: That’s the way (that) she spoke. = That’s how she spoke. I should like to know the way/how you learned to master the fundamental technique within so short a time. 4.the way的其它用法:以上我们讲的都是用作先行词的the way,下面我们将叙述它的一些用法。

定冠词the的12种用法

定冠词the的12种用法 定冠词the 的12 种用法,全知道?快来一起学习吧。下面就和大家分享,来欣赏一下吧。 定冠词the 的12 种用法,全知道? 定冠词the用在各种名词前面,目的是对这个名词做个记号,表示它的特指属性。所以在词汇表中,定冠词the 的词义是“这个,那个,这些,那些”,可见,the 即可以放在可数名词前,也可以修饰不可数名词,the 后面的名词可以是单数,也可以是复数。 定冠词的基本用法: (1) 表示对某人、某物进行特指,所谓的特指就是“不是别的,就是那个!”如: The girl with a red cap is Susan. 戴了个红帽子的女孩是苏珊。 (2) 一旦用到the,表示谈话的俩人都知道说的谁、说的啥。如:

The dog is sick. 狗狗病了。(双方都知道是哪一只狗) (3) 前面提到过的,后文又提到。如: There is a cat in the tree.Thecat is black. 树上有一只猫,猫是黑色的。 (4) 表示世界上唯一的事物。如: The Great Wall is a wonder.万里长城是个奇迹。(5) 方位名词前。如: thenorth of the Yangtze River 长江以北地区 (6) 在序数词和形容词最高级的前面。如: Who is the first?谁第一个? Sam is the tallest.山姆最高。 但是不能认为,最高级前必须加the,如: My best friend. 我最好的朋友。 (7) 在乐器前。如: play the flute 吹笛子

Way的用法

Way用法 A:I think you should phone Jenny and say sorry to her. B:_______. It was her fault. A. No way B. Not possible C. No chance D. Not at all 说明:正确答案是A. No way,意思是“别想!没门!决不!” 我认为你应该打电话给珍妮并向她道歉。 没门!这是她的错。 再看两个关于no way的例句: (1)Give up our tea break? NO way! 让我们放弃喝茶的休息时间?没门儿! (2)No way will I go on working for that boss. 我决不再给那个老板干了。 way一词含义丰富,由它构成的短语用法也很灵活。为了便于同学们掌握和用好它,现结合实例将其用法归纳如下: 一、way的含义 1. 路线

He asked me the way to London. 他问我去伦敦的路。 We had to pick our way along the muddy track. 我们不得不在泥泞的小道上择路而行。 2. (沿某)方向 Look this way, please. 请往这边看。 Kindly step this way, ladies and gentlemen. 女士们、先生们,请这边走。 Look both ways before crossing the road. 过马路前向两边看一看。 Make sure that the sign is right way up. 一定要把符号的上下弄对。 3. 道、路、街,常用以构成复合词 a highway(公路),a waterway(水路),a railway(铁路),wayside(路边)

way与time的特殊用法

way/time的特殊用法 1、当先行词是way意思为”方式.方法”的时候,引导定语从句的关系词有下列3种形式: Way在从句中做宾语 The way that / which he explained to us is quite simple. Way在从句中做状语 The way t hat /in which he explained the sentence to us is quite simple. 2、当先行词是time时,若time表示次数时,应用关系代词that引导定语从句,that可以省略; 若time表示”一段时间”讲时,应用关系副词when或介词at/during + which引导定语从句 1.Is this factory _______ we visited last year? 2.Is this the factory-------we visited last year? A. where B in which C the one D which 3. This is the last time _________ I shall give you a lesson. A. when B that C which D in which 4.I don’t like the way ________ you laugh at her. A . that B on which C which D as 5.He didn’t understand the wa y ________ I worked out the problem. A which B in which C where D what 6.I could hardly remember how many times----I’ve failed. A that B which C in which D when 7.This is the second time--------the president has visited the country. A which B where C that D in which 8.This was at a time------there were no televisions, no computers or radios. A what B when C which D that

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