2006-@@Cultivated microalgae and the carotenoid fucoxanthin from=FX=抗癌-齿状藻-金藻

Environmental Toxicology and Pharmacology22(2006)

97–103

Cultivated microalgae and the carotenoid fucoxanthin from

Odontella aurita as potent anti-proliferative agents

in bronchopulmonary and epithelial cell lines

Dimitri Moreau a,?,Christophe Tomasoni a,Catherine Jacquot a,Raymond Kaas b,

Roland Le Guedes b,Jean-Paul Cadoret b,Arnaud Muller-Feuga b,Ioanna Kontiza c,

Constantinos Vagias c,Vassilios Roussis c,Christos Roussakis a

a Laboratoire de Pharmacologie Marine,ISOMer,Facult′e de Pharmacie de Nantes,1rue Gaston Veil,BP92208,44322Nantes Cedex03,France

b Laboratoire de Physiologie et Biotechnologie des Algues,IFREMER,rue de l’??le d’Yeu,BP1105,44311Nantes Cedex03,France

c University of Athens,Department of Pharmacy,Division of Pharmacognosy an

d Chemistry of Natural Products,

Panepistimiopolis Zografou,Athens15771,Greece

Received10November2005;accepted9January2006

Available online6March2006

Abstract

The antiproliferative activities of several extracts from cultivated microalgae in France have been studied against bronchopulmonary and epithelial cell lines,respectively(A549,NSCLC-N6and SRA01/04).The algal extracts,of Diatomae(Odontella aurita,Chaetoseros sp.),as well as of Haptophyceae:Isochrisys aff.galbana,appeared as the most active among all the assayed species,expressing a broad spectrum of in vitro antiproliferative activity of well-differentiated pathologic cells such as NSCLC-N6by terminal differentiation.Bio-guided fractionation of the above referred extracts,led us to the isolation,of the carotenoid fucoxanthin.Fucoxanthin has been structurally determined,through modern spectral means and has been studied separately for its activities.

?2006Elsevier B.V.All rights reserved.

Keywords:Odontella aurita;Antiproliferative activities;Bronchopulmonary carcinoma;Secondary cataract;Apoptosis;Fucoxanthin

1.Introduction

Marine microalgae comprise the largest group of living organisms in the oceans,constituting an estimated10,000 species.Algae are at the base of entire aquatic food chain.There-fore,it is not surprising that the microalgae,which compose the phytoplankton,play a vital role in the rearing of aquatic animals like molluscs;shrimps and?sh.Moreover,there are numerous applications for molecules from these phototropic microorganisms in human and animal food,health and cosme-tology(Muller-Feuga,2000).

In recent years,there has been a growing interest in functional foods,that is,foods able to provide additional physiological bene?ts for human health,other than the basic nutritional and

?Corresponding author.Tel.:+33251125672;fax:+33251125690.

E-mail address:dimitri.moreau@univ-nantes.fr(D.Moreau).energetic requirements(Bidlack,1994).Often,functional foods are traditional foods enriched with an ingredient able to pro-vide or promote a speci?c bene?cial action for human health. These are called functional ingredients.These ingredients are preferred to have a natural origin,such as plants or perhaps algae and/or microalgae.These types of marine sources are receiving increasing attention mainly for their content in,for example,polyunsaturated fatty acids and,?-carotene and other pigments(antioxidants),sulphated polysaccharides and sterols (antimicrobials).

One of the main interests in our laboratories is to assess the suitability obtained from extracts and pure compounds from cul-tivated microalgae,like the ones which they have been studied, as food antioxidants and preventative agents against secondary cataracte and cancer.

In this work,a preliminary screening of ten marine and fresh water species from different orders(Diatomophyceae, Rhodophyceae,Haptophyceae,Cryptophyceae,Prasinophyceae

1382-6689/$–see front matter?2006Elsevier B.V.All rights reserved. doi:10.1016/j.etap.2006.01.004

98 D.Moreau et al./Environmental Toxicology and Pharmacology22(2006)97–103

Table1

Detail of the different strains studied,with the source and the optimal condition of growing

Order Species Source Medium pH T(?C) Diatomophyceae Odontella aurita IFREMER Conway7.520 Chaetoceros https://www.sodocs.net/doc/8e10815747.html,ap1010/11Conway7.520

Porphyridium purpureum SAG111/79Hemerick720 Rhodophyceae Rhodella violacea SAG115/79Conway724 Galdieria sulphuraria a074W Galdi245 Chlorophyceae Chlamydomonas reinhardtii a PG27MMG/TAP724 Haptophyceae Isochrysis af?nis galbana IFREMER Conway720 Cryptophyceae Rhodomonas salina ccap978/24Conway722 Prasinophyceae Tetraselmis suecica ccmp904Conway720 Dinophyceae Heterocapsa triquetra IFREMER ESP7.822 G.sulphuraria source:Institut f¨u r biologie,Freie Universit¨a t,Berlin.

a Fresh water microalgae.

and Dinophyceae)were investigated as natural source of antipro-liferative agents in vitro against asynchronous cells of human non-small-cell bronchopulmonary carcinoma line(NSCLC-N6) (Roussakis et al.,1991),human lung epithelial cell line(A549)and against a proliferative human lens epithelial cell line(SRA 01/04).Bio-guided fractionation of the extracts,which appeared as the most active,led us to the isolation of the carotenoid fucox-anthin,which has been also thoroughly assayed.In all cases,the

Table2

Composition of the different media used for algal culture

Products Medium

Hemerick Conway Galdi MMG/TAP ESP NaNO3(g L?1) 1.70.10.07 (NH4)2SO4(g L?1) 1.5

NH4Cl(g L?1)0.4

K2HPO4,3H2O(g L?1)0.1750.106

KH2PO4(g L?1)0.1750.30.053

NaH2PO4,H2O(g L?1)0.02

Na2C3H7O6P,5H2O(g L?1)0.01 Na2SiO3,5H2O(g L?1)0.1

FeEDTA0.050.014

Na2EDTA,2H2O(g L?1)0.0490.0450.008 CaCl2,2H2O(g L?1) 1.470.020.05

KCl(g L?1)0.75

MgSO4,7H2O(g L?1)12.30.30.1

MgSO4,H2O(g L?1)0.00082 NaCl(g L?1)29.0

Tris(g L?1)0.1

Co(NO3)2,6H2O(?g L?1)0.08

CoCl2,6H2O(?g L?1)20.080 2.927

CoSO4,7H2O(?g L?1)0.09124 CuSO4,5H2O(?g L?1)0.0820.0160 2.855

Fe(NH4)2(SO4)2,6H2O(?g L?1)3510 FeCl3,6H2O(?g L?1) 1.3245 FeSO4,7H2O(?g L?1)9.073

H3BO3 2.033.6572020.735700 MnCL2,4H2O(?g L?1) 1.80.3636409.2

Mo7O24(NH4)6,4H2O(?g L?1)209.0260 2.0

NaVO3,4H2O(?g L?1)80

O5SV,5H2O(?g L?1)0.043

ZnCl2(?g L?1)21

ZnSO4,7H2O(?g L?1)0.2130.444011000 Vitamin B12(?g L?1)102 Thiamin(?g L?1)200100 Biotin(?g L?1)1

QSP L(?g L?1)FW MW FW FW MW Mineral nutrient and their concentration(1×).

D.Moreau et al./Environmental Toxicology and Pharmacology22(2006)97–10399 Table3

IC50for all assayed microalgal extracts,with different solvents,against three cell lines

Species Cell lines

SRA A549NSCLC-N6

EtOH CH2Cl2H2O EtOH CH2Cl2H2O EtOH CH2Cl2H2O

O.aurita18.4±1.418.2±0.49.1±1.3––20.6±0.555.8±3.736.9±1.542.6±5.8 Chaetoceros sp.15.5±0.513.5±0.97.8±0.3–41.5±3.861.1±8.6–13.5±2.4–

P.purpureum––0.5±0.1––13.9±0.4–– 6.3±0.5 R.violacea–26.7±2.550.8±2.6––––––

G.sulphuraria41.3±3.810±0.6<0.366±0.05–37.3±2.59.1±1.3–18.7±2.5 4.8±0.5 C.reinhardtii––11.1±0.3––16±2.2–36.6±0.624.6±2 I.af?nis galbana20.7±3.425.4±1.726.2±1.424.6±1.340.7±2.6–21.6±4.314.5±1.817.3±2.8 R.salina28.1±1.58.2±1.5–––––––

T.suecica–12.3±2.5–––––45.3±10.117.6±5 H.triquetra19.7±1.436.8±1.58.2±1.6–––21.4±2.4–13.8±0.3 The results are expressed in?g/ml.

studied organisms were isolated from natural population and cultured in controlled manner in laboratory(Muller-Feuga et al.,2003).

In the literature,there are several reports on the fatty acid, lipid,amino-acids and sugar composition of almost all microal-gae used in mariculture(V olkman et al.,1989;Servel et al.,1989; Brown,1991),because mostly of the importance of these data, for determining the nutritional value of the microalgae as food for animals in mariculture.Especially for the diatom Odontella aurita,the isolation and structure elucidation of a new sterol sul-fate has been published(Toume and Ishibashi,2002).No studies have been reported,to our knowledge,on any other chemical constituents of the assayed microalgae.

2.Materials and methods

2.1.Microalgal materials,culture conditions and chemicals

Studied species were isolated from their natural environment and were cul-tured in our laboratory.All parameters of culture(different sources of strains, culture media,pH,growing temperature conditions)are presented in details in Table1.Details on the composition of several media used are presented in Table2.Unialgal cultures were carried out in batch conditions in10l glass bot-tles,under constant light and aeration(air/CO2mixture,99:1).Every4days the medium was supplemented with1×nutrient(Table2),until the cell concentra-tion achieved the stationary phase.

Water in all cases was sterile and distilled and solvents were analytical grade Cyclohexane(Lab-scan),EtOAc(Lab-scan),MeOH...Acetone,DMSO,etc.

2.2.Preparation of algal extracts

All algae were recovered from culture,in the stationary phase,by centrifuga-tion at low speed and low temperature(4?C).The algal residue was freeze dried before extraction and then it was then re-suspended in ethanol100%(400ml/g of dried weight),dichloromethane(400ml/g of dried weight)and water,respec-tively,so that three extracts of different polarities to be prepared.All extracts were?ltered,and evaporated under vacuum at low temperature(<45?C).All organic extracts were dissolved with dimethyl sulfoxide(DMSO)and diluted in water at1mg/ml,before testing on cancer cell line.The?nal concentration of DMSO used to dissolve extracts did not exceed0.2%and had no effect on the proliferation of the cells(results not shown).Aqueous extracts were directly diluted in water at1mg/ml.

2.3.Strains and media,cell lines ad culture

The NSCLC-N6-L16cell line(Roussakis et al.,1991),derived from a human non-small-cell bronchopulmonary carcinoma(moderately differentiated,rarely keratinizing,classi?ed as T2N0M0),and A549obtained from ATCC collection reference CCL6185(Giard et al.,1973),were used for all experiments.Both cell lines were cultured in RPMI1640medium with5%fetal calf serum,to which were added100IU penicillin ml?1,100?g streptomycin ml?1and2mM glutamine,at37?C in an air/carbon dioxide(95:5v/v)atmosphere.In these conditions,cell doubling time was48h.Cells used in all experiments never exceeded35passages.

Human Lens Epithelial cell line,SRA01/04,which was established by transfection with large T-antigen of SV40(Ibaraki et al.,1998)was cultured in antibiotic-free Dulbecco’s modi?ed Eagle’s medium(DMEM)(Biochrom KG) supplemented with4%foetal calf serum and incubated in the same conditions described for L16and A549.

2.4.Cytotoxicity determinations:continuous drug exposure

Experiments were performed in96wells microtiter plates(105cells ml?1 for NSCLC-N6,2×104cells ml?1for A549and3×104cells ml?1for SRA). Cell growth was estimated by a colorimetric assay based on the conservation of tetrazolium dye(MTT)to a blue formazan product by live mitochondria (Mosmann,1983).Eight repeats were performed for each concentration.Control growth was estimated from eight determinations.Optical density at570

nm Fig.1.Chemical structure of fucoxanthin.

100 D.Moreau et al./Environmental Toxicology and Pharmacology22(2006)97–103

corresponding to solubilized formazan was read for each well on a Titertek Multiskan MKII.

2.5.Cytotoxicity determinations:discontinuous drug exposure

Cells were incubated for72h in96wells microtiter at the concen-tration of5×104cells ml?1for NSCLC-N6,104cells ml?1for A549and 1.5×104cells ml?1for SRA in the culture conditions described above,and in the presence or absence of the drug.After72h medium was removed,cells were washed with phosphate-buffered saline to eliminate drug traces,and then100?l fresh medium containing no drug were placed in each wells.Cell growth was evaluated by the colorimetric assay of Mosmann using MTT(Mosmann,1983).

2.6.Extractions and solvent fractionation

Due to the results of cytotoxic assays,the dichloromethane extract of O. aurita was primary selected for the bio-guided fractionation and the isolation and determination of the active compounds.Then total dichloromethane extract was?rst subjected to silica gel column chromatography(CC),using mixtures of CH2Cl2/acetone/EtOH(from CH2Cl2100%to EtOH100%),to afford?ve frs.:fr.1has been eluted with CH2Cl2,fr.2with100%CH2Cl2,fr.3with CH2Cl2/acetone(70:30),fr.4with CH2Cl2/acetone(50:50),and?nally fr.5with 100%EtOH.After testing on NSCLC-N6cell lines,the only active fraction(fr.3) was further puri?ed after has been subjected to vacuum column chromatography on silica gel(VLC,60H,Merck).Fifteen fractions were obtained(named frs.

3.1–3.15),using100ml of mixtures of cyclohexane/EtOAc/MeOH of increasing polarity.After a new test of the puri?ed extract,the identi?cation of active compound was done through modern spectral means.

The[M]+ion of compound3.10atm.m/z658,in combination with the 13C NMR data required a C42H58O6molecular formula.Characteristic were the overlapping peaks atδ6.09–6.69ppm consisted with conjugated double bonds intergrading for nine protons.Obvious were four singlets at1.92,1.97, 1.79,1.97resulting from four vinylic methyls,as well as a multiplet peak at5.36due to an oxidized methine.Moreover characteristic was at the13C NMR spectrum the presence of an allene moiety[δc117.5(C-6 ),202.4(C-7 ), 103.5(C-8 ).These evidences lead to the assumption that compound3.10was (3S,5R,6S,3 S,5 R,6 R)-fucoxanthine,also according to international literature (Haugan et al.,1992).

2.7.Detection of apoptotic cells in fucoxanthin

The detections of apoptotic cells were performed for all three cell lines under the same conditions.Cells were incubated in the presence of15?g/ml fucoxan-thin for72h;for the studied of DNA fragmentation,the DNA was extract with a classical phenol/chloroform protocol.Then an electrophoresis was performed on agarose gel for all the DNA extracts.For the observation of apoptotic cells, they were stained with10?g/ml of acridin orange for15min in the dark.The results were observed using a?uorescence microscope,Olympus AX70?,with exciter?lter BP450-480.

3.Results and discussion

3.1.Inhibitory effect of algal extracts on cell lines

For each one of the tested extracts,the concentration required to reduce cell growth by50%(IC50)was determined and results are shown in Table3for all cell lines.Almost a73%of the assayed extracts showed moderate to strong activity against SRA cell line,while only53%and30%exhibited activity against NSCLC-N6and A549cell lines,respectively.

3.2.Chemical composition of active compound from

O.aurita

The concentration of frs.3and3.10required to reduce L16 cell growth by50%was determined as previously described,and their IC50were found8.5and7?g ml?1,respectively,after72h of treatment.Through the NMR spectra as well through inter-national literature it has been identi?ed that fr.3.10was pure fucoxanthin Fig.1.The thin layer chromatography of Chaeto-ceros sp.and I.aff.galbana dichloromethane extracts show a wide quantity of fucoxanthin as for O.aurita,certainly respon-sible of the activities observed.

3.3.Growth inhibition by continuous and discontinuous

drug exposure

Fig.2illustrated the growth kinetics of NSCLC-N6cells in the presence(from5to20?g ml?1)and absence(control)of the fucoxanthin.The inhibitory effect of fucoxanthin was

dose-Fig.2.Effect of the carotenoid fucoxanthin on the cell growth of NSCLC-N6 (a);A549(b)and SRA(c)cell-lines:growth kinetics versus time after continuous exposure to drug at different concentrations.The proliferation is reduced for the three cell line in a dose dependant manner and we can observe a plateau after 24h of treatment.

D.Moreau et al./Environmental Toxicology and Pharmacology22(2006)97–103

101

Fig.3.Effect of fucoxanthin on the cell growth of the NSCLC-N6(a),A549 (b),SRA(c)cell lines:growth kinetics versus time after discontinuous exposure to drug at different concentrations.The cell growth is apparently blocked after 72h of treatment for the three cell lines at different concentration. dependent and only observed with a continuous drug exposure. The pro?le obtained was typical of cytostatic activity.Fig.3 depicted the growth pattern of NSCLC-N6cell line in a drug free medium with populations pre-treated for72h in the pres-ence(10–25?g ml?1)and absence(control)of fucoxanthin. This results show that the effect of fucoxanthin is irreversible and con?rm its cytostatic activity against NSCLC-N6cell-line since10?g/ml.

3.4.Induction of apoptosis

Fig.4has been showed that the treatment by fucoxanthin induces a DNA fragmentation typical of apoptotic cells.It can be seen a typical fragment around185bp(Au et al.,1997). The electrophoresis showed also,the same DNA ladder for the bronchopulmonary cell lines treated by fucoxanthin.

The Fig.4.Agarose gel electrophoresis of the DNA extract from witness and treated cells with15?g/ml https://www.sodocs.net/doc/8e10815747.html,ne(1):DNA marker(SmartLadder?,euro-gentec),lanes(2,3)NSCLC-N6,lanes(4,5)A549.

exposure of the cells to fucoxanthin for72h,clearly induced morphological change such as rounding up,reduction of cell volume,chromatin condensation,nuclei fragmentation and for-mation of apoptotic bodies for the two bronchopulmonary cells lines(Figs.4and5).For SRA no apoptosis induction has been observed.

Indeed,the greatest interests of microalgae,is that they can be produced in controlled condition with a low cost,and that they are adapted to a wide variety of environments favour to an exceptional biochemical production.In this study,a screening of new antiproliferative compounds from10different species of microalgae,has been taken place.So,a preliminary study of their crude extracts was?rst necessary to evaluate the presence of new potent cytotoxic and/or cytostatic compounds.Then,the results have been demonstrated,the real extraordinary potential of the microalgae for the discovery of active extracts.Through this screening,it has been already permitted to identify more than10 extracts active on three cell lines and two different pathologies.

After the identi?cation,through the bioguided fractionation, of the carotenoid fucoxanthin as the responsible agent of the activity observed by the dichloromethane extracts of the diatoms microalgae,it has been also investigated the cytostatic activ-ity of this molecule.The expressed antiproliferative effect of this compound,has been studied by characterizing the kinetics of cell growth induced by continuous and acontinuous treat-ment and observing the induced apoptosis.Through all these parameters observed,can be suggested that fucoxanthin could trigger the terminal differentiation of cancerous cells in vitro. It has been already reported that fucoxanthin induces apoptosis in human leukemia,prostate and colon cancer cells(Kotake-Nara et al.,2001;Hosokawa et al.,1999,2004).Furthermore, it has been previously also demonstrated,an inhibitory effect of fucoxanthin on N-myc expression and on cell cycle progres-sion for human neuroblastoma cell line(Okuzumi et al.,1990). But it is the?rst time that it has been demonstrated an arrest in

102 D.Moreau et al./Environmental Toxicology and Pharmacology 22(2006)

97–103

Fig.5.Observation of cells stained with acridin orange.Morphological comparison by ?uorescence microscopy of treated cells by fucoxanthin and control cells (a,b)NSCLC-N6;(c,d)A549.

G0/G1phase of the GOTO cells by fucoxanthin as well as that induces apoptosis in lung cancer and in human lens epithelial cells.

The structures of carotenoids are of great interest,in the reduction of growth as well as in apoptosis induction,against cancer cells.Many studies have been also reported the antiox-idant activity of fucoxanthin (Nomura et al.,1997;Murakami et al.,2000).In contrast,the pro-oxidant action of carotenoids is shown to induce apoptosis through the production of reac-tive oxygen species (Palozza et al.,2003).This suggests that carotenoids act either as an antioxidant or as a pro-oxidant,in dependence on their environment.

In conclusion,the studied microalgae appeared to be ef?-cient and safe antiproliferative agents.Interestingly,the species O.aurita ,Chaetoceros sp.and I.aff.galbana are proved as rich sources of the carotenoid fucoxanthin.This molecule exhibited cytostatic activity and this effect could have important implica-tions for the application of mixtures of this kind of microalgae in food manufacturing and the formulation of ocular implant products used in cataract treatment.References

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字母组合th的读音规则总结完整版

字母组合t h的读音规 则总结 标准化管理处编码[BBX968T-XBB8968-NNJ668-MM9N]

字母组合th的读音规则总结 现就中学英语课本中出现的含有字母组合th的单词，进行分类归纳，对其在单词中的读音总结以下几条。 1．在th后以字母-er结尾的单词中，th读浊辅音/e/。 例：altogether/:lt'gee/，farther/'fae/， feather/'fe e/，whether/'we e/，either/'aie/， gather/'ge/ 2．一般情况下，在代词、冠词、介词、连词或副词中的字母组合th，读浊辅音/e/。 例：within/wi'ein/，without/wi'eaut/，these/ei:z/，therefore/'eef:/，al-though/:leu/，those/ euz/，the/ e/，thus/ eas/ 发音特殊的单词：through/θru:/，throughout/θru:'aut/ 3．字母组合th在数词（包括基数词和序数词）中读清辅音/θ/。 例：three/θri:/，thirty/'θ:ti/，thirteen/'θ:'ti:n/， third/ θ:d/，fourth/f:θ/，fiftieth/'fiftiiθ/， thousand/'θauznd/，hundredth/'handrdθ/ 4．除上述单词外，一般位于词首的th读/θ/。 例：theatre/'θit/，thick/θik/，thin/θin/，throat/θrut/， theory/'θiri/，thrust/θrast/，thread/θred/，thorough/'θar/， Thursday/'θ:zdi/ 5．以th结尾的单词，th读清辅音/θ/。 例：truth/tru:θ/，worth/w:θ/，breath/breθ/，both/buθ/，cloth/klθ/，path/pa:θ/，wealth/welθ/，length/leθ/，strength/streθ/

th发音规律

辅音字符th 有清与浊两种读音： 1 当位于词首时，可以从词性上判别其应有的读音。请看： 第一类：在以下4种词类th 读清音，即国际音标的θ ： a. Noun 名词：thing, theatre, thumb大拇指, thunder雷, thermos热水瓶, Thursday, theory, theme, throat喉咙, thread线 b. Verb 动词：think, thank, throw, thrive, thicken, c.Numeral 数词：three, thirteen, thirty, third, thousand d.Adjective 形容词：thin, thick, thirsty, thoughtful, thorough彻底的 第二类：在以下两种词类th 读浊音： a. Pronoun 代词：they, them, their, theirs, this, these, that, those, there, thy[旧时用法]你的 b. Functional terms 功能词：the, than, then, though, thus, therefore 2 当位于词尾（或音节之尾）时，其读音多数是清音，如：bath, breath, both, cloth, tooth, health, wealth, arithmetic 等。只有在少数单词中，如：with, smooth 中读浊音。 3 当位于两个元音之间时，其读音多数是浊音。如：other, mother, brother, another, father, weather, feather, leather, further, breathe. 但是，也有读清音的。如在单词 method, nothing, anything, sympathy, sympathetic, mathematics, healthy, wealthy, Luther, Marathon(马拉松)等

Th字母组合在单词中的发音

th字母组合的发音规律 1．在th后以字母-er结尾的单词中，th读浊辅音/e/。 例：altogether/?:lt?'gee?/， farther/'fae?/， feather/'fe e?/， whether/'we e?/，either/'aie?/，gather/'g?e?/ 2．一般情况下，在代词、冠词、介词、连词或副词中的字母组合th，读浊辅音/e/。 例：within/wi'ein/，without/wi'eaut/，these/ei:z/，therefore/'ee?f?:/， al-though/?:le?u/，those/ e?uz/，the/ e?/，thus/ eas/ 发音特殊的单词：through/θru:/，throughout/θru:'aut/ 3．字母组合th在数词（包括基数词和序数词）中读清辅音/θ/。 例：three/θri:/，thirty/'θ?:ti/，thirteen/'θ?:'ti:n/，third/ θ?:d/，fourth/f?:θ/，fiftieth/'fiftiiθ/， thousand/'θauz?nd/，hundredth/'handr?dθ/ 4．除上述单词外，一般位于词首的th读/θ/。 例：theatre/'θi?t?/，thick/θik/，thin/θin/， throat/θr?ut/，theory/'θi?ri/，thrust/θrast/， thread/θred/，thorough/'θar?/，Thursday/'θ?:zdi/ 5．以th结尾的单词，th读清辅音/θ/。

例：truth/tru:θ/，worth/w?:θ/，breath/breθ/，both/b?uθ/，cloth/kl?θ/，pa th/pa:θ/，wealth/welθ/，length/le?θ/，strength/stre?θ/ 发音特殊的单词，例：smooth/smu:e/ 6．在复合词中，th的读音与在原词中的读音相同。 例：something / 'samθi?/，anything/'eniθi?/，nothing/'naθi?/ 还有前面提到的within，without等。 7．其他无规则可循的词分列如下： maths/m?θs/，arithmetic/?'riθm?tik/， clothing/kl?uei?/， clothes/kl?uez/，southern/'sae?n/，northern/'n?:e?n ／， worthy/'w?:ei/，author/'?:θ?/，sympathy/'simp?θi/

英语音标：字母组合th的读音规则总结

英语音标：字母组合th的读音规则总结1．在th后以字母-er结尾的单词中，th读浊辅音/J/。 例：altogether/&：lt+'geJ+/，farther/'fa J+/，feather/'fe J+/， whether/'we J+/，either/'ai J+/，gather/'g J+/ 2．一般情况下，在代词、冠词、介词、连词或副词中的字母组合th，读浊辅音/J/。 例：within/wi'Jin/，without/wi'Jaut/，these/Ji：z/，therefore/'>J#+f&：/，al-though/&：lJ+u/，those/ J+ uz/，the/ J+/，thus/ J)s/ 发音特殊的单词：through/Iru：/，throughout/'Iru：aut/ 3．字母组合th在数词（包括基数词和序数词）中读清辅音/I/。 例：three/Iri&：/，thirty/'I+：ti/，thirteen/'I+：'ti：n/， third/ I+：d/，fourth/f &：I/，fiftieth/'fiftii I/， thousand/'Iauz+nd/，hundredth/'h)ndr+dI/ 4．除上述单词外，一般位于词首的th读/I/。 例：theatre/'Ii+t+/，thick/Iik/，thin/Iin/，throat/Ir+ut/，theory/'Ii+ri/，thrust/Ir)st/，thread/Ired/，thorough/')r+/，Thursday/'I+：zdi/ 5．以th结尾的单词，th读清辅音/I/。 例：truth/tru：I/，worth/w+ ：I/，breath/breI/， both/b+uI/，cloth/kl&I/，path/pa ：I/，wealth/welI/， length/leRI/，strength/streRI/

th在英语单词中的发音

一、如何区分th在英语单词中的发音 1. th位于词首时，可以从词性上判别其应有的读音。在名词、动词、形容词和数词中th发清辅音。如：thing, theatre, thunder, thermos, Thursday, theory, theme, throat, think, thank, , thicken, thirteen, thirty, third, thousand, thick, thirsty, 2. 在代词和一些功能词中th发浊辅音.如：them, their, theirs, there, the, than, then, though, therefore, they。只有介词through是个例外。 3. th位于词尾（或音节之尾）时，其读音多数是清辅音，如：bath, breath, tooth, 等。只有在少数单词中，如：with, smooth 中读浊音。 4. th在词中并且后面接er时，或者最后一个字母是不发音的e时，通常也发浊辅音。例如：feather, weather, whether, leather, further, father, bathe, breathe, southern, northern, either等。在其他情况下发清辅音。例如：faithful, method, nothing, anything, healthy, wealthy。 试读下列单词: mother, father, another, brother, health, wealth 二、如何区分单词后加“ed”后，这个ed怎么读 规则动词加ed后的发音：清念/t/ ,元浊/d/ ; /t/ /d/ 之后念/id/ 1、以清辅音结尾(不包括在词尾发音的t和d),加了-ed后,发/t/ .例：finished helped passed cooked 2、.以元音或浊辅音结尾的,加了-ed后,发/d/. 例：borrowed enjoyed called moved 3、结尾是发音的t或d,加了-ed后,发/id/. 例：wanted shouted needed counted 三、如何区分单词后加“s”或“es”后，这个单词的读音。 1、大多数动词在词尾加“S”在清辅音后发音为[s]，在浊辅音及元音后发音为[z]。 如：①stop－stops[s];make－makes[s]②read－reads[z];play－plays[z] 2、以辅音字母加“y”结尾的，要先将“y”变为“i”，然后在加“es”读[iz]如： fly－flies[z]；carry－carries[z] study－studies[z];worry－worries 3、以“s,x,ch,sh”结尾的，在词尾加“es”，发音为[iz]如： teach－teaches[iz];watch－watches[iz] 4、以“o”结尾的动词，加“es”，读[z]如：go－goes[z]do－does[z] 5. 以不发音字母“e”结尾的开音节词，如果尾音是[s]，[z]时，加“s”后字母“e”发 音，与所加“s”一起读做[iz]。如：close－closes[iz]

字母在单词中的发音

字母在单词中的发音 元音字母在单词中的发音 开音节 1）以发音的元音字母结尾的单节。例：be，he。 2）以辅音字母（r 除外）+不发音的e结尾的音节。例：make，like。 * 在重读的开音节中元音字母按字母名称读音。 闭音节 以一个或几个辅音字母（r 除外）结尾而中间只有一个元音字母的音节， 称为闭音节。例：map，desk，is。 * 在重读的闭音节中元音字母读做短元音。 Aa [ei] 在单词中的发音 1. 在重读开音节中发字母音[ei] a age able ache bake cake snake wake lake make take case cable age save base tape wave date race face name same game frame gate hate male pale sale taste shave shade race plane plate place page space safe slave state table stable stage skate paste trace trade waste (注意have[] ,ate []和vase的英国发音) 2. 在重读闭音节中发[?] at act ash bag bad bat cap cat can dad fact hand jam black thank rabbit glad chat van vat sad

3. 在非重读音节中发[?] a'go a'wake a'live a'lone a'long a'side a'board a'broad a'round a'bout a'bove a'ccept a'djust a'like American a'mount a'sleep a'ware a'way a'part 'panda 'cinema 4. 在重读-r音节中发[α:] car star start far arm army hard farm party card part pardon March farther farthest garden harvest market large apart parking (注意"[w]+ar" ,ar发[?:] warm war toward quarter [] ; 在非重读-r音节中发[?] 'sugar) 5. 在-re音节中发[e] care hare careful parent (注意are[α:] ) 6. 在重读闭音节中,"a+age"字母组合中,发[ei] dange dangerous strange stranger change exchange (注意orange [] ) 7. 在重读闭音节中,"a+ss, a+st, a+sp, a+sk, a+th, a+f, a+n" 中的a 发[α:] glass class classmate grass pass passer-by last fast past grasp ask mask basketball rather father after afternoon dance answer France plant can't 8. 在重读闭音节中,a前是w时,a常发[] want wash washer watch was (注意water [] ) Aa 的字母组合音节在单词中的发音

字母组合th的读音规则总结

字母组合th的读音规则总结 现就中学英语课本中出现的含有字母组合th的单词，进行分类归纳，对其在单词中的读音总结以下几条。 1．在th后以字母-er结尾的单词中，th读浊辅音/e/。 例：altogether/?:lt?'gee?/，farther/'fae?/，feather/'fe e?/，whether/'we e?/，either/'aie?/，gather/'g?e?/ 2．一般情况下，在代词、冠词、介词、连词或副词中的字母组合th，读浊辅音/e/。 例：within/wi'ein/，without/wi'eaut/，these/ei:z/，therefore/'ee?f?:/，al-though/?:le?u/，those/ e?uz/，the/ e?/，thus/ eas/ 发音特殊的单词：through/θru:/，throughout/θru:'aut/ 3．字母组合th在数词（包括基数词和序数词）中读清辅音/θ/。 例：three/θri:/，thirty/'θ?:ti/，thirteen/'θ?:'ti:n/， third/ θ?:d/，fourth/f?:θ/，fiftieth/'fiftiiθ/， thousand/'θauz?nd/，hundredth/'handr?dθ/ 4．除上述单词外，一般位于词首的th读/θ/。 例：theatre/'θi?t?/，thick/θik/，thin/θin/，throat/θr?ut/，theory/'θi?ri/，thrust/θrast/，thread/θred/，thorough/'θar?/，Thursday/'θ?:zdi/ 5．以th结尾的单词，th读清辅音/θ/。 例：truth/tru:θ/，worth/w?:θ/，breath/breθ/，both/b?uθ/，cloth/kl?θ/，path/pa:θ/，wealth/welθ/，length/le?θ/，

字母组合th的读音规则

字母组合th的读音规则 现就中学英语课本中出现的含有字母组合th的单词，进行分类归纳，对其在单词中的读音总结以下几条。 1．在th后以字母-er结尾的单词中，th读浊辅音/J/。 例：altogether/&：lt+'ge J+/，farther/'fa J+/，feather/'fe J+/， whether/'we J+/，either/'ai J+/，gather/'g J+/ 2．一般情况下，在代词、冠词、介词、连词或副词中的字母组合th，读浊辅音/J/。 例：within/wi'J in/，without/wi'J aut/，these/J i：z/，therefore/'>J#+f&：/， al-though/&：l J+u/，those/ J+ uz/，the/ J+/，thus/ J)s/ 发音特殊的单词：through/I ru：/，throughout/'I ru：aut/ 3．字母组合th在数词（包括基数词和序数词）中读清辅音/I/。 例：three/I ri&：/，thirty/'I+：ti/，thirteen/'I+：'ti：n/， third/ I+：d/，fourth/f &：I/，fiftieth/'fiftii I/， thousand/'I auz+nd/，hundredth/'h)ndr+d I/ 4．除上述单词外，一般位于词首的th读/I/。 例：theatre/'I i+t+/，thick/I ik/，thin/I in/，throat/I r+ut/，theory/'I i+ri/，thrust/I r)st/，thread/I red/，thorough/')r+/，Thursday/'I+：zdi/ 5．以th结尾的单词，th读清辅音/I/。 例：truth/tru：I/，worth/w+ ：I/，breath/bre I/，both/b+u I/，cloth/kl&I/，path/pa：I/，wealth/wel I/，length/le RI/，strength/stre RI/ 发音特殊的单词，例：smooth/smu：J/ 6．在复合词中，th的读音与在原词中的读音相同。 例：something / 's)m I i R/，anything/'eni I i R/，nothing/'n^)I i R/ 还有前面提到的within，without等。

字母组合th发音

字母组合th发音[e] 一、发音训练模块. that this these those they them father 那这这些那些他们他们爸爸 clothes the there then their with mother 衣服这那儿那时他们的带妈妈 二、短语训练模块。 this book that book this child these books those books these childen 三、句子训练模块（there be句型）。 四、阅读扩展训练模块（读句子）。 Good morning!My name is Zhang Li.I’m Chinese.I am in No 14 Middle School.I am a student(学生).I’m at school. My teacher is Miss Green.My mother is in No.14 Middle School,too.She is a teacher ,and she is a Chinese teacher. 根据短文内容判断下列句子的正(T)，误(F)。(10分)

( )1.My teacher is my mother. ( )2.It’s morning. ( )3.My mother and I are in the same(同样的)school. ( )4.My mother is an English teacher. ( )5.Zhang Li is at school. 五、口语训练模块。 1. --What time is it now? ----现在几点钟? -----It’s nine o’clock.It’s time for English class. 九点。该上英语课了。 -----It’s eight o’clock. It’s time to go to bed. 八点。该上床睡觉了。 2. --What day is it today? ----今天星期几? ----It’s Monday. ----星期一。 六、there be句子训练模块。

th的发音规则22365教学总结

t h的发音规则22365

精品资料 辅音字符th清与浊的两种读音规则：一、当位于词首时，可以从词性上判别其应有的读音。 第一类：四种词类th读清音，即国际音标的/θ/： 1、Noun名词：thing, theatre, thumb大拇指, thunder雷, Thursday throat喉咙theory, theme主题 2、Verb动词：think, thank, throw,扔，投掷 3、Numeral数词：three, thirteen, thirty, third, thousand 4、Adjective形容词：thin, thick, thirsty, thorough彻底的 第二类：在以下两种词类th读浊音/e/： 1、Pronoun代词：they, them, their, theirs, this, these, that, those, there, 2、Functional terms功能词：the, than, then, though, thus, therefore 二、当位于词尾（或音节之尾）时： 1、多数是清音/θ/。如：bath, breath, both, cloth, tooth, health, wealth等。 2、少数单词读浊音/e/。如：with, smooth等。 三、当位于两个元音之间时： 1、多数是浊音/e/如：other, mother, brother, another, father, weather等。 2、也有读清音的/θ/ 如：method, nothing, anything, healthy, wealthy等。

th的发音规则说课讲解

t h的发音规则

辅音字符th清与浊的两种读音规则：一、当位于词首时，可以从词性上判别其应有的读音。 第一类：四种词类th读清音，即国际音标的/θ/： 1、Noun名词：thing, theatre, thumb大拇指, thunder雷, Thursday throat喉咙theory, theme主题 2、Verb动词：think, thank, throw,扔，投掷 3、Numeral数词：three, thirteen, thirty, third, thousand 4、Adjective形容词：thin, thick, thirsty, thorough彻底的 第二类：在以下两种词类th读浊音/e/： 1、Pronoun代词：they, them, their, theirs, this, these, that, those, there, 2、Functional terms功能词：the, than, then, though, thus, therefore 二、当位于词尾（或音节之尾）时： 1、多数是清音/θ/。如：bath, breath, both, cloth, tooth, health, wealth等。 2、少数单词读浊音/e/。如：with, smooth等。 三、当位于两个元音之间时： 1、多数是浊音/e/如：other, mother, brother, another, father, weather等。 2、也有读清音的/θ/ 如：method, nothing, anything, healthy, wealthy等。 注意：发出地道的“th”：将你的舌尖略微伸出嘴，上齿轻咬舌尖部位,气流通过舌齿间的缝隙，将音发出。要留一条缝隙，否则音发不出来。

th的发音规则

辅音字符th清与浊的两种读音规则 一、当位于词首时，可以从词性上判别其应有的读音。 第一类：四种词类th 读清音，即国际音标的/θ/： 1、名词：thing, theatre, thumb, thunder, thermos, Thursday 2、动词：think, thank, throw, thrive, thicken, 3、数词：three, thirteen, thirty, third, thousand 4、形容词：thin, thick, thirsty, thoughtful, thorough 第二类：在以下两种词类th 读浊音： 1、代词：they, them, their, theirs, this, these, that, those, there, 2、功能词：the, than, then, though, thus, therefore 二、当位于词尾（或音节之尾）时。 1、多数是清音。如：bath, breath, both, cloth, tooth, health, wealth, 等。 2、少数单词读浊音。如：with, smooth等。 三、当位于两个元音之间时。 1、多数是浊音。如：other, mother, brother, another, father, weather等。 2、也有读清音的。如method, nothing, anything, healthy, wealthy等。 辅音字符th清与浊的两种读音规则 一、当位于词首时，可以从词性上判别其应有的读音。 第一类：四种词类th 读清音，即国际音标的/θ/： 1、名词：thing, theatre, thumb, thunder, thermos, Thursday 2、动词：think, thank, throw, thrive, thicken, 3、数词：three, thirteen, thirty, third, thousand 4、形容词：thin, thick, thirsty, thoughtful, thorough 第二类：在以下两种词类th 读浊音： 1、代词：they, them, their, theirs, this, these, that, those, there, 2、功能词：the, than, then, though, thus, therefore 二、当位于词尾（或音节之尾）时。 1、多数是清音。如：bath, breath, both, cloth, tooth, health, wealth, 等。 2、少数单词读浊音。如：with, smooth等。 三、当位于两个元音之间时。 1、多数是浊音。如：other, mother, brother, another, father, weather等。 2、也有读清音的。如method, nothing, anything, healthy, wealthy等。

字母组合th的读音规则

字母组合 th 的读音规则 现就中学英语课本中出现的含有字母组合 th 的单词，进行分类归纳，对其在单词中的读 音总结以下几条。 1．在 th 后以字母 -er 结尾的单词中， th 读浊辅音 / J/ 。 例： altogether/ & ： lt +'ge J+/ ， farther/'fa J+/ ， feather/'fe J+/ ， whether/'we J+/ ， either/'ai J+/ ， gather/'g J+/ 2．一般情况下，在代词、冠词、介词、连词或副词中的字母组合th ，读浊辅音 /J/ 。 例： within/wi' Jin/ ， without/wi' Jaut/ ，these/ Ji ：z/ ， therefore/' >J#+f & ：/， al-though/ & ：l J+u/ ， those/ J+ uz/ ， the/ J+/ ， thus/ J)s/ 发音特殊的单词： through/ Iru ： / ， throughout/' Iru ：aut/ 3．字母组合 th 在数词(包括基数词和序数词)中读清辅音 / I/ 。 例： three/ Iri &：/ ， thirty/' I+：ti/ ， thirteen/' I+ ： 'ti ：n/ ， third/ I+：d/ ， fourth/f & ： I / ， fiftieth/'fiftii I/， thousand/' I auz+ nd/ ， hundredth/'h )ndr +dI/ 4．除上述单词外，一般位于词首的th 读 / I/ 。 例： theatre/' Ii +t +/ ， thick/ Iik/ ， thin/ Iin/ ， throat/ Ir+ut/ ， theory/' Ii +ri/ ， thrust/ Ir )st/ ， thread/ Ired/ ， thorough/' )r + / ， Thursday/' I+ ： zdi/ 5．以 th 结尾的单词， th 读清辅音 / I/ 。 例：truth/tru : I/ , worth/w + ： I/ , breath/bre 1/ , both/b +ul/ , cloth/kl &I / , path/pa I/， wealth/wel I/， length/le RI/， strength/stre RI/ 发音特殊的单词，例： smooth/smu ： J/ 6．在复合词中，th 的读音与在原词中的读音相同。 例：something / 's )mli R/ , anything/'eni li R/ , nothing/'n A)l

th的发音规则

t h的发音规则 公司内部档案编码：[OPPTR-OPPT28-OPPTL98-OPPNN08]

辅音字符th清与浊的两种读音规则：一、当位于词首时，可以从词性上判别其应有的读音。 第一类：四种词类th读清音，即国际音标的/θ/： 1、Noun名词：thing, theatre, thumb大拇指, thunder雷, Thursday throat喉咙theory, theme主题 2、Verb动词：think, thank, throw,扔，投掷 3、Numeral数词：three, thirteen, thirty, third, thousand 4、Adjective形容词：thin, thick, thirsty, thorough彻底的 第二类：在以下两种词类th读浊音/e/： 1、Pronoun代词：they, them, their, theirs, this, these, that, those, there, 2、Functional terms功能词：the, than, then, though, thus, therefore 二、当位于词尾（或音节之尾）时： 1、多数是清音/θ/。如：bath, breath, both, cloth, tooth, health, wealth等。 2、少数单词读浊音/e/。如：with, smooth等。 三、当位于两个元音之间时： 1、多数是浊音/e/如：other, mother, brother, another, father, weather等。 2、也有读清音的/θ/ 如：method, nothing, anything, healthy, wealthy等。 注意：发出地道的“th”：将你的舌尖略微伸出嘴，上齿轻咬舌尖部位,气流通过舌齿间的缝隙，将音发出。要留一条缝隙，否则音发不出来。

th的发音规则 ()

辅音字符t h清与浊的两种读音规则 一、当位于词首时，可以从词性上判别其应有的读音。 第一类：四种词类th读清音，即国际音标的/θ/： 1、名词：thing,theatre,thumb,thunder,thermos,Thursday 2、动词：think,thank,throw,thrive,thicken, 3、数词：three,thirteen,thirty,third,thousand 4、形容词：thin,thick,thirsty,thoughtful,thorough 第二类：在以下两种词类th读浊音： 1、代词： they,them,their,theirs,this,these,that,those,there, 2、功能词：the,than,then,though,thus,therefore 二、当位于词尾（或音节之尾）时。 1、多数是清音。如：bath,breath,both,cloth,tooth,health,wealth,等。 2、少数单词读浊音。如：with,smooth等。 三、当位于两个元音之间时。 1、多数是浊音。如：other,mother,brother,another,father,weather等。 2、也有读清音的。如method,nothing,anything,healthy,wealthy等。 辅音字符th清与浊的两种读音规则 一、当位于词首时，可以从词性上判别其应有的读音。 第一类：四种词类th读清音，即国际音标的/θ/： 1、名词：thing,theatre,thumb,thunder,thermos,Thursday 2、动词：think,thank,throw,thrive,thicken, 3、数词：three,thirteen,thirty,third,thousand 4、形容词：thin,thick,thirsty,thoughtful,thorough 第二类：在以下两种词类th读浊音： 1、代词： they,them,their,theirs,this,these,that,those,there, 2、功能词：the,than,then,though,thus,therefore 二、当位于词尾（或音节之尾）时。 1、多数是清音。如：bath,breath,both,cloth,tooth,health,wealth,等。 2、少数单词读浊音。如：with,smooth等。 三、当位于两个元音之间时。 1、多数是浊音。如：other,mother,brother,another,father,weather等。

th的发音规则

一、当位于词首时，可以从词性上判别其应有的读音。 第一类：四种词类 th 读清音，即国际音标的/θ/： 1、名词：thing, theatre, thumb, thunder, thermos, Thursday 2、动词：think, thank, throw, thrive, thicken, 3、数词：three, thirteen, thirty, third, thousand 4、形容词：thin, thick, thirsty, thoughtful, thorough 第二类：在以下两种词类 th 读浊音： 1、代词：they, them, their, theirs, this, these, that, those, there, 2、功能词：the, than, then, though, thus, therefore 二、当位于词尾（或音节之尾）时。 1、多数是清音。如：bath, breath, both, cloth, tooth, health, wealth, 等。 2、少数单词读浊音。如：with, smooth等。 三、当位于两个元音之间时。 1、多数是浊音。如：other, mother, brother, another, father, weather 等。 2、也有读清音的。如method, nothing, anything, healthy, wealthy等。 辅音字符th清与浊的两种读音规则 一、当位于词首时，可以从词性上判别其应有的读音。 第一类：四种词类 th 读清音，即国际音标的/θ/： 1、名词：thing, theatre, thumb, thunder, thermos, Thursday 2、动词：think, thank, throw, thrive, thicken, 3、数词：three, thirteen, thirty, third, thousand 4、形容词：thin, thick, thirsty, thoughtful, thorough 第二类：在以下两种词类 th 读浊音： 1、代词：they, them, their, theirs, this, these, that, those, there, 2、功能词：the, than, then, though, thus, therefore 二、当位于词尾（或音节之尾）时。 1、多数是清音。如：bath, breath, both, cloth, tooth, health, wealth, 等。 2、少数单词读浊音。如：with, smooth等。 三、当位于两个元音之间时。 1、多数是浊音。如：other, mother, brother, another, father, weather

英语中th的发音规则

th在英语中的发音规则 发音2008-12-14 22:23:05 阅读469 评论0 字号：大中小订阅 A:将你的舌尖略微伸出嘴，上齿轻咬舌尖部位,气流通过舌齿间的缝隙，将音发出。注意：要留一条缝隙，否则音发不出来。最扎实可行的方法就是多练习，可以连发1000遍，只要肯下工夫，绝对可以发出地道 的“th”。 辅音字符th 有清与浊两种读音： 1 当位于词首时，可以从词性上判别其应有的读音。 请看： 第一类：在以下4种词类th 读清音，即国际音标 的θ ： a. Noun 名词：thing, theatre, thumb大拇指, thunder 雷, thermos热水瓶, Thursday, theory, theme, throat喉 咙, thread线 b. Verb 动词：think, thank, throw, thrive, thicken,

c.Numeral 数词：three, thirteen, thirty, third, thousand d.Adjective 形容词：thin, thick, thirsty, thoughtful, thorough彻底的 第二类：在以下两种词类th 读浊音： a. Pronoun 代词：they, them, their, theirs, this, these, that, those, there, thy[旧时用法]你的 b. Functional terms 功能词：the, than, then, though, thus, therefore 2 当位于词尾（或音节之尾）时，其读音多数是清音，如：bath, breath, both, cloth, tooth, health, wealth, arithmetic 等。只有在少数单词中，如：with, smooth 中读浊音。 3 当位于两个元音之间时，其读音多数是浊音。如：other, mother, brother, another, father, weather,

th的发音规则

辅音字符th清与浊的两种读音规则：一、当位于词首时，可以从词性上判别其应有的读音。 第一类：四种词类th读清音，即国际音标的/θ/： 1、Noun名词：thing, theatre, thumb大拇指, thunder雷, Thursday throat喉咙theory, theme主题 2、Verb动词：think, thank, throw,扔，投掷 3、Numeral数词：three, thirteen, thirty, third, thousand 4、Adjective形容词：thin, thick, thirsty, thorough彻底的 第二类：在以下两种词类th读浊音/e/： 1、Pronoun代词：they, them, their, theirs, this, these, that, those, there, 2、Functional terms功能词：the, than, then, though, thus, therefore 二、当位于词尾（或音节之尾）时： 1、多数是清音/θ/。如：bath, breath, both, cloth, tooth, health, wealth等。 2、少数单词读浊音/e/。如：with, smooth等。 三、当位于两个元音之间时： 1、多数是浊音/e/如：other, mother, brother, another, father, weather等。 2、也有读清音的/θ/ 如：method, nothing, anything, healthy, wealthy等。 注意：发出地道的“th”：将你的舌尖略微伸出嘴，上齿轻咬舌尖部位,气流通过舌齿间的缝隙，将音发出。要留一条缝隙，否则音发不出来。

英语单词中th

英语单词中th、oo、s的发音规律 一、单词中th的发音规律 (1)th位于词首时，可以从词性上判别其应有的读音。 在名词、动词、形容词和数词中th发清辅音。如： thing, theatre, thunder, thermos, Thursday, theory, theme, throat, th read, think, thank, thrive, thicken, thirteen, thirty, third, thousand, thick, thirs ty, thoughtful, thorough 在代词和一些功能词中th发浊辅音. 如： them, their, theirs, there, the, than, then, though, thus, ther efore, they 只有介词through是个例外。 (2) th位于词尾（或音节之尾）时，其读音多数是清辅音，如： bath, breath, tooth, 等。只有在少数单词中，如：with, smooth 中读浊音。 (3) th 在词中并且后面接er时，或者最后一个字母是不发音的e时，通常也发浊辅音。例如： feather, weather, whether, leather, further, father, bathe, breathe, southern, northern,either , mother, another, brother等。 (4)在其他情况下发清辅音。例如： author, faithful, method, nothing, anything, health , healthy, wealth y。 二、单词中OO的发音规律 oo读长还是短,记住口诀就简单。 d, k之前读短[u],food一词是特例; t前读长[u:],foot需要特殊记; 复合词中要读短,其余多数读长[u:]; l, s, d间读作[Λ],例外还要特殊记。 oo在单词中的发音主要有长音[u:]和短音[u]两种: