The effects of phospholipids on crystallisation and crystal habit in triglycerides

?WILEY-VCH Verlag GmbH, 69451 Weinheim, 2000

0931-5985/2000/0202-0122 $17.50+.50/0

1Introduction

Triglyceride crystallisation is a complex phenomenon that has interested researchers for many years. It is compli-cated by the slow growth rates and the polymorphic be-haviour of fats. Despite this the behaviour is fairly well-known and a useful review is that edited by Garti and Sato [1].

The effects of impurities and emulsifiers or surfactants further complicate triglyceride crystallisation, whether they are present by accident or design in a system. They may be added to a system for emulsification or surfactant behaviour or they may be present as natural impurities.Some work has been published on the effects of different emulsifiers on fat blends [2–4]. However, there appears to have been little systematic work to understand underlying interaction mechanisms. W?hnelt et al. [5, 6] have shown that the addition of diglycerides can retard the crystal growth of cocoa butter. The author has investigated the effects of partial glycerides on model fat systems [7, 8]. In these papers models for the interactions of impurities and additives with crystallising fats have begun to be devel-oped. It has been shown that the shape and size of the additive molecule are critically important in determining its interaction with the crystallising triglyceride molecules.The nature of the effect that occurs is dependent upon the

relative sizes and shapes of the different molecules. Ef-fects on both the growth rate and resultant crystal shape occur.

The polymorphic form, shape, and size of the fat crystals are important in ensuring that a fatty product has the re-quired physical properties. Great care is often taken dur-ing product processing in order to achieve optimal prod-uct properties.

The general crystal morphologies of the three major poly-morphic forms of triglycerides have been well charac-terised for a great number of years. In 1960 Hoerr [9] de-scribed the three forms thus:

α:Very thin, less than several μm in size, smooth surface.β’:Long needle shape (Size distribution <5μm).β:Large, plate-like crystals, 20–100 μm in size.

More-detailed morphologies of βcrystals of different triglycerides have been determined by various authors [10–11].

Thus, the change from one polymorphic form to another leads to a very large modification to the crystals’morphol-ogy. However, by controlling crystallisation of a polymor-phic form, more subtle changes of habit can be achieved.Molecules that affect the crystallisation are likely to inter-act in different ways with the different faces of a growing crystal, so that crystal habit modification can be achieved.This process is well established in the chemical industry

Paul R. Smith

Institute for Surface Chem-istry, Stockholm, Sweden

The effects of phospholipids on crystallisation and crystal habit in triglycerides

Many food products contain a network of fat crystals. The sizes and shapes of these triglyceride crystals are extremely important in producing the good physical properties and texture for a high-quality final product. Control of crystal habit can affect a fat’s structure and hence the resultant behaviour. In this work the effects of phospholipids on the crystal habit of triglyceride crystals have been investigated. Optical and scan-ning electron microscopy, DSC, and X-ray diffraction have been used. The effects of certain phospholipids on the crystallisation of fats have been shown, and large changes to crystal habit have been demonstrated. These changes are caused by the interactions of the phospholipid molecules with the crystallising triglyceride molecules.Interference with the crystallising molecules causes changes to the shape and size (habit) of the resultant fat crystals. Effects on nucleation and crystal growth are demon-strated. These dramatic changes to the crystal habit can have a significant effect on the properties of the resultant fat system. For example the process of fat fractionation could be significantly enhanced. Alternatively, the network structure of fatty products could be controlled or altered opening up the possibility of the development of new and improved products.

Keywords:

Triglyceride, habit, crystallisation, phospholipid.

R e s e a r c h P a p e r

as a means for modifying crystal habits, as discussed by Lewtas et al. [12]. However, there has been very little sys-tematic attempt to couple measurements on the effects of additives on the crystallisation of triglycerides with any ef-fects on habit modification.

Phospholipids are very commonly used as emulsifiers and surfactants in fat-based systems. Interactions be-tween phospholipids and triglycerides are therefore im-portant. Effects of phospholipid molecules on triglyceride crystallisation and crystal habit could be particularly im-portant in many systems.

The objective of this work is to consider the effects of phospholipids on the crystallisation behaviour of both model and natural fats. The effects of the interactions be-tween the molecules have been studied and effects on crystallisation and crystal habit have been noted. Thus, interaction models can be developed and so potential ap-plications for the use of phospholipids in foods processing determined.

2 Materials and methods

Phospholipids (soy bean lecithin and pure phosphatidyl choline [1-2-diacyl-sn-glycero-3-phosphocholine], phos-phatidyl ethanolamine [1,2-diacyl-sn-glycero-3-phospho-ethanolamine] and phosphatidyl inositol [1,2-diacyl-sn-glycero-3-phospho-[1-D-myo-inositol]], as well as phos-phatidyl cholines of differing chain length) and pure glyc-erides were obtained from Sigma Chemical Co., Stock-holm, Sweden. The phospholipids used were from natural sources of soy bean, bovine brain, and egg yolk. Addi-tionally, synthetic phosphatidyl cholines with controlled side chain composition were obtained. Materials with side chains of C12to C18were obtained and used. Karlshamns AB,Karlshamn, Sweden supplied palm oil.

Mixtures of 0.1, 0.2, 0.5, and 1 weight-% of phospholipids were prepared in palm oil, trilaurin, and tristearin. Sam-ples were heated to approximately 80 °C, with stirring, and dissolution of the additive was ensured.

2.1 Initial screening

Mixtures of 20 ml of palm oil with and without phospho-lipids were heated to 80 °C and stirred until dissolution of the phospholipid had occurred. They were then left overnight at 20 °C. The mixtures were then observed and samples taken for microscopy. A control sample contain-ing no phospholipid was also prepared and tested in the same manner.2.2 Temperature gradient microscopy

A temperature gradient microscopy system was designed and built according to the manner of Hunt et al. [13]. The system was used as previously described [7, 8]. Samples of trilaurin plus 0.2 weight-% phosphatidyl ethanolamine and phosphatidyl choline were studied. Samples were studied at forced crystallisation rates of between 10 and 100 °C per hour.

2.3 Scanning electron microscopy

A portion of the material from the initial screening was tak-en and as much liquid as possible was filtered off. The sample was then thoroughly washed with acetone at the same temperature to remove all remaining traces of oil without damaging the solid. The remaining solid was then quenched in liquid nitrogen, gold-coated, and observed.

2.4 Differential scanning calorimetry

Differential scanning calorimetry was performed using a Perkin-Elmer DSC 7calorimeter. Samples of trilaurin plus 0.1, 0.2, 0.5, and 1 weight-% phosphatidyl ethanolamine or phosphatidyl choline were prepared. Samples were cooled from 60 °C to –20 °C at 3 °C per min.

2.5 Laboratory-scale fractionation

Simple laboratory-scale dry fractionation was performed on selected systems of palm oil plus 0.2 weight-% phos-pholipid. Samples of 100 ml of oil were prepared. They were then heated to 60 °C and cooled in air to 20 °C. At this temperature palm oil has a relatively low solid content of about 12% and so a dispersion of liquid and solid was formed. The samples were then filtered under vacuum and the yields of olein and stearin measured.

3 Results

3.1 Initial screening

After the screening procedure the control sample of palm oil was apparently solid and homogeneous (despite a cal-culated solid content of only about 12%). Samples con-taining phosphatidyl ethanolamine showed obvious differ-ences with much larger spherulites. At a concentration of 0.5% phosphatidyl ethanolamine liquid oil could be easily poured off. This was not possible at all with the control sample.

The microstructure of the control sample is illustrated in Fig. 1. It consists of small spiky spherulites that interlock to form a net-like structure. Individual crystals are long and very thin (needle-like), are heavily twinned and are of varying length. This gives the appearance of the ragged-looking spherulites.

Samples containing phosphatidyl ethanolamine, phos-phatidyl inositol and lysophosphatidyl ethanolamine had similar structure to each other. Much larger spherulites were observed which were more uniform in size (Fig. 2). The spiky nature of the spherulites was largely reduced and the interlocking net-like structure was much dimin-ished. The presence of the larger spherulites indicates a retardation effect on the nucleation, whereas the change in the structure shows a modification effect on growth and crystal habit.

The phosphatidyl choline containing samples also gave larger spherulites than the control (Fig. 3), however, in this case there is no change to the spherulitic structure or the shape or size of the individual crystals. This suggests that the phosphatidyl choline is acting in a different man-ner to the other investigated compounds. There is still an effect on the nucleation, but very little effect on crystal growth.

Scanning electron microscopy (SEM) pictures of the sam-ples confirm these observations (Fig. 4). They show that the structure of the spherulites is significantly altered by the addition of phosphatidyl ethanolamine. A very clear change to the crystal structure is illustrated, as well as the obvious change in crystal size.

3.2 Differential scanning calorimetry

In general additives retarded the crystallisation transfor-mation with phosphatidyl ethanolamine having a much larger effect than phosphatidyl choline (Fig. 5). This showed that the additives are inhibiting the crystallisation of the triglycerides, with additives that are having a larger effect on the crystal habit again here having a larger ef-fect.

A further series of experiments was performed with the addition of synthetic phosphatidyl choline of varying side-chain length from C12to C18. It was found that they all re-duced the nucleation and crystallisation rates with an in-creasing effect with chain length and so the palmitoyl (C16) and stearoyl (C18) compounds had the greatest effect. This shows that chain length is an important factor for considering the effects of an additive and suggests that matching or near matching of chain length gives larger interaction and effect.

3.3 Temperature gradient microscopy Comparison between trilaurin and trilaurin plus PE sam-ples are shown in Fig. 6. The addition of phosphatidyl ethanolamine caused certain changes to crystal habit. In particular the crystals’aspect ratios are increased and

Fig. 1. Spherulites of palm oil.Fig. 2. Spherulites of palm oil plus 0.2 weight-% phos-

phatidyl ethanolamine.

Fig. 3. Spherulites of palm oil plus 0.2 weight-% phos-

phatidyl choline.

Fig. 4. (a) SEM micrograph of palm oil spherulites, (b) SEM micrograph of spherulites of palm oil plus 0.2 weight-% phos-

phatidyl ethanolamine.

Fig. 6. Micrographs taken on the temperature gradient microscope stage. (a) Trilaurin, (b) Trilaurin plus 0.2% phosphatidyl ethanolamine.

Fig. 5. Solid content vs tem-perature on DSC cooling of trilaurin (LLL), trilaurin plus 0.2% phosphatidyl choline (+PC) and trilaurin plus 0.2%phosphatidyl ethanolamine (+PE).

Fig. 7. Growth of crystals of trilaurin (LLL), trilaurin plus phosphatidyl choline (+PC) and trilaurin plus phosphatidyl

ethanolamine (+PE) measured on the temperature gradient microscope stage.Fig. 8. Yields from the laboratory scale dry fractionation experiments. Samples contain on added phospholipid (control),phosphatidyl ethanolamine (PE), phosphatidyl choline (PC), or phosphatidyl inositol (PI).

there is variation to the characteristic interfacial angles.This shows a large classical effect on the relative growth of the different faces.

Crystal growth rates were measured (Fig. 7). It is clearly shown that the phospholipids retard growth in the fastest

growing direction. This indicates that the phospholipids have strong effects on crystal growth as well as any ef-fects that they have on crystal nucleation. Also, different additives have different effects. Therefore, the exact mechanism depends upon the interaction between the particular additive and the growing triglyceride crystals.

3.4 Laboratory-scale fractionation

Laboratory-scale fractionations were performed on cer-tain systems. In particular systems containing phos-phatidyl ethanolamine and phosphatidyl choline were studied. Yields are given in Fig. 8. As the real solid con-tent is unchanged from one sample to the next any re-duction in the “stearin” apparent solid content is due to less entrapped oil in the solid. Therefore, a higher sepa-ration efficiency is indicated. In this case it can be seen that phosphatidyl choline has a negligible effect on the separation efficiency, whereas phosphatidyl ethanol-amine improves the separation efficiency by a large amount.

4 Discussion

The results demonstrate how minor components can have a significant effect on the crystallisation behaviour of triglycerides. They show how the addition of controlled quantities of additives can lead to changes in the struc-ture of crystals and so alter the crystal network of a par-ticular system. As a result significant changes can be made in the efficiency of a process or in the behaviour of a product. This technology has been investigated for frac-tionation application to destroy fat crystal structures and optimise fractionation yields [14, 15]. However, by under-standing the mechanisms that are occurring it should be possible to increase network strength and so produce products which have stronger networks. This may be use-ful to entrap oils in a fat crystal network at a lower content of fat than is possible without crystal habit control.

5 Conclusions

Interactions between additives and triglycerides can sig-nificantly alter the shape and size of the fat crystals. This can then have a large effect on the properties of any fat crystal network and thus on the properties of a system (e.g. food product). By control of the interaction different effects are possible. Further work is required in order to relate the mechanisms of the triglycerides: additive inter-actions to the resultant behaviour of final systems. Acknowledgements

The Institute for Research and Competence Holding AB (IRECO) is thanked for financial support. Hans Ringblom performed much of the experimental work.References

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and Fatty Acids, Surfactant Science Series 31, Marcel Dekker (New York) 1988.

[2]I. Niiya, E. Moire, M. Imamura, M. Okada, T. Matsumoto:Ef-

fect of emulsifiers on the crystal growth of solid edible fat.

Jpn J. Food Sci. 18 (1969) 583–591.

[3] E. Sambuc, Z. Dirik, M. Naudet: Study of the crystallisation

of plastic fats. Rev. Fr. Corps Gras 27 (1980) 505–511. [4]N. Garti, E. Wellner, S. Sarig: Crystal structure modifica-

tions of tristearin by food emulsifiers. J. Am. Oil Chem. Soc.

59 (1982) 181–185.

[5]S. W?hnelt, D. Meusel, M. Tülsner: Influence of diglyc-

erides on the phase behaviour of edible fats. Fat Sci. Tech-nol. 93 (1991) 117–121.

[6]S. W?hnelt, D. Meusel, M. Tülsner:Influence of isomeric

diglycerides on phase transitions of cocoa butter – Investi-gation by isothermal differential scanning calorimetry. Fat Sci. Technol. 93 (1991) 174–178.

[7]P. R. Smith, D. J. Cebula, M. J. W. Povey:The effect of lau-

ric-based molecules on trilaurin crystallisation. J. Am. Oil Chem. Soc. 71 (1994) 1367–1372.

[8]P. R. Smith, M. J. W. Povey:The effect of partial glycerides

on trilaurin crystallisation. J. Am. Oil Chem. Soc. 74 (1997) 169–171.

[9] C. W. Hoerr:Morphology of fats, oils and shortenings. J.

Am. Oil Chem. Soc. 37 (1960) 539–544.

[10]M. Okada:The transformation of tristearin crystal from

α-form to β-form by melt growth method. J. Electronmi-croscopy 13 (1964) 180–186.

[11]P. Bennema, L. J. P. Vogels, S. de Jong:Morphology of

β-phase monoacid triacylglycerol crystals: Theory and ob-servations. J. Cryst. Growth 123 (1992) 141–152.

[12]K. Lewtas, R. D. Tack, D. M. H. Beiny, J. W. Mullin:Wax

crystallisation in diesel fuel: Habit modification and the growth of n-alkane crystals. In: Advances in Industrial Crystallisation, Eds. J. Garside, R. J. Davey, A. G. Jones, Butterworth-Heinemann (Oxford) 1991, pp. 166–183. [13]J. D. Hunt, K. A. Jackson, H. Brown:The temperature gra-

dient microscope stage. Rev. Sci. Instrum. 37 (1966) 805–808.

[14]M. van den Kommer, P. R. Smith, A. Visser, C. Winkel, D. J.

Cebula:U.S. Pat. 5,602,265, Van den Berghs Food Co. [15]P. R. Smith, M. van den Kommer:U.S. Pat. 5,621,125, Van

den Berghs Food Co.

[Received: July 23, 1999; accepted: November 9, 1999]

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一般过去式 时间状语：yesterday just now (刚刚) the day before three days ag0 a week ago in 1880 last month last year 1. I was in the classroom yesterday. I was not in the classroom yesterday. Were you in the classroom yesterday. 2. They went to see the film the day before. Did they go to see the film the day before. They did go to see the film the day before. 3. The man beat his wife yesterday. The man didn’t beat his wife yesterday. 4. I was a high student three years ago. 5. She became a teacher in 2009. 6. They began to study english a week ago 7. My mother brought a book from Canada last year. 8.My parents build a house to me four years ago . 9.He was husband ago. She was a cooker last mouth. My father was in the Xinjiang half a year ago. 10.My grandfather was a famer six years ago. 11.He burned in 1991

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英语句子结构和造句

高中英语~词性~句子成分~语法构成 第一章节：英语句子中的词性 1.名词：n. 名词是指事物的名称，在句子中主要作主语.宾语.表语.同位语。 2.形容词;adj. 形容词是指对名词进行修饰~限定~描述~的成份，主要作定语.表语.。形容词在汉语中是（的）.其标志是: ous. Al .ful .ive。. 3.动词：vt. 动词是指主语发出的一个动作，一般用来作谓语。 4.副词：adv. 副词是指表示动作发生的地点. 时间. 条件. 方式. 原因. 目的. 结果.伴随让步. 一般用来修饰动词. 形容词。副词在汉语中是（地）.其标志是：ly。 5.代词：pron. 代词是指用来代替名词的词，名词所能担任的作用，代词也同样.代词主要用来作主语. 宾语. 表语. 同位语。 6.介词：prep.介词是指表示动词和名次关系的词，例如：in on at of about with for to。其特征：

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六级单词解析造句记忆MNO

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意见应以事实为根据. 3 来自辞典例句 192. The bombers swooped ( down ) onthe air base. 轰炸机 突袭 空军基地. 来自辞典例句 193. He mounted their engines on a rubber base. 他把他们的发动机装在一个橡胶垫座上. 14 来自辞典例句 194. The column stands on a narrow base. 柱子竖立在狭窄的地基上. 14 来自辞典例句 195. When one stretched it, it looked like grey flakes on the carvas base. 你要是把它摊直, 看上去就象好一些灰色的粉片落在帆布底子上. 18 来自辞典例句 196. Economic growth and human well - being depend on the natural resource base that supports all living systems. 经济增长和人类的福利依赖于支持所有生命系统的自然资源. 12 1 来自辞典例句 197. The base was just a smudge onthe untouched hundred - mile coast of Manila Bay. 那基地只是马尼拉湾一百英里长安然无恙的海岸线上一个硝烟滚滚的污点. 6 来自辞典例句 198. You can't base an operation on the presumption that miracles are going to happen. 你不能把行动计划建筑在可能出现奇迹的假想基础上.

英语造句大全

英语造句大全English sentence 在句子中，更好的记忆单词！ 1、(1)、able adj. 能 句子：We are able to live under the sea in the future. (2)、ability n. 能力 句子：Most school care for children of different abilities. (3)、enable v. 使。。。能句子：This pass enables me to travel half-price on trains. 2、(1)、accurate adj. 精确的句子：We must have the accurate calculation. (2)、accurately adv. 精确地 句子：His calculation is accurately. 3、(1)、act v. 扮演 句子：He act the interesting character. （2）、actor n. 演员 句子：He was a famous actor. (3)、actress n. 女演员 句子：She was a famous actress. (4)、active adj. 积极的 句子：He is an active boy. 4、add v. 加 句子：He adds a little sugar in the milk. 5、advantage n. 优势 句子：His advantage is fight. 6、age 年龄n. 句子：His age is 15. 7、amusing 娱人的adj. 句子：This story is amusing. 8、angry 生气的adj. 句子：He is angry. 9、America 美国n.

(完整版)主谓造句

主语+谓语 1. 理解主谓结构 1) The students arrived. The students arrived at the park. 2) They are listening. They are listening to the music. 3) The disaster happened. 2．体会状语的位置 1) Tom always works hard. 2) Sometimes I go to the park at weekends.. 3) The girl cries very often. 4) We seldom come here. The disaster happened to the poor family. 3. 多个状语的排列次序 1) He works. 2) He works hard. 3) He always works hard. 4) He always works hard in the company. 5) He always works hard in the company recently. 6) He always works hard in the company recently because he wants to get promoted. 4. 写作常用不及物动词 1. ache My head aches. I’m aching all over. 2. agree agree with sb. about sth. agree to do sth. 3. apologize to sb. for sth. 4. appear (at the meeting, on the screen) 5. arrive at / in 6. belong to 7. chat with sb. about sth. 8. come (to …) 9. cry 10. dance 11. depend on /upon 12. die 13. fall 14. go to … 15. graduate from 16. … happen 17. laugh 18. listen to... 19. live 20. rise 21. sit 22. smile 23. swim 24. stay (at home / in a hotel) 25. work 26. wait for 汉译英： 1.昨天我去了电影院。 2.我能用英语跟外国人自由交谈。 3.晚上7点我们到达了机场。 4.暑假就要到了。 5.现在很多老人独自居住。 6.老师同意了。 7.刚才发生了一场车祸。 8.课上我们应该认真听讲。9. 我们的态度很重要。 10. 能否成功取决于你的态度。 11. 能取得多大进步取决于你付出多少努力。 12. 这个木桶能盛多少水取决于最短的一块板子的长度。

初中英语造句

【it's time to和it's time for】 ——————这其实是一个句型,只不过后面要跟不同的东西. ——————It's time to跟的是不定式（to do）.也就是说,要跟一个动词,意思是“到做某事的时候了”.如： It's time to go home. It's time to tell him the truth. ——————It's time for 跟的是名词.也就是说,不能跟动词.如： It's time for lunch.(没必要说It's time to have lunch) It's time for class.(没必要说It's time to begin the class.) They can't wait to see you Please ask liming to study tonight. Please ask liming not to play computer games tonight. Don’t make/let me to smoke I can hear/see you dance at the stage You had better go to bed early. You had better not watch tv It’s better to go to bed early It’s best to run in the morning I am enjoy running with music. With 表伴随听音乐 I already finish studying You should keep working. You should keep on studying English Keep calm and carry on 保持冷静继续前行二战开始前英国皇家政府制造的海报名字 I have to go on studying I feel like I am flying I have to stop playing computer games and stop to go home now I forget/remember to finish my homework. I forget/remember cleaning the classroom We keep/percent/stop him from eating more chips I prefer orange to apple I prefer to walk rather than run I used to sing when I was young What’s wrong with you There have nothing to do with you I am so busy studying You are too young to na?ve I am so tired that I have to go to bed early

The Kite Runner-美句摘抄及造句

《The Kite Runner》追风筝的人--------------------------------美句摘抄 1.I can still see Hassan up on that tree, sunlight flickering through the leaves on his almost perfectly round face, a face like a Chinese doll chiseled from hardwood: his flat, broad nose and slanting, narrow eyes like bamboo leaves, eyes that looked, depending on the light, gold, green even sapphire 翻译：我依然能记得哈桑坐在树上的样子，阳光穿过叶子，照着他那浑圆的脸庞。他的脸很像木头刻成的中国娃娃，鼻子大而扁平，双眼眯斜如同竹叶，在不同光线下会显现出金色、绿色，甚至是宝石蓝。 E.g.: A shadow of disquiet flickering over his face. 2.Never told that the mirror, like shooting walnuts at the neighbor's dog, was always my idea. 翻译：从来不提镜子、用胡桃射狗其实都是我的鬼主意。E.g.:His secret died with him, for he never told anyone. 3.We would sit across from each other on a pair of high

翻译加造句

一、翻译 1. The idea of consciously seeking out a special title was new to me., but not without appeal. 让我自己挑选自己最喜欢的书籍这个有意思的想法真的对我具有吸引力。 2.I was plunged into the aching tragedy of the Holocaust, the extraordinary clash of good, represented by the one decent man, and evil. 我陷入到大屠杀悲剧的痛苦之中，一个体面的人所代表的善与恶的猛烈冲击之中。 3.I was astonished by the the great power a novel could contain. I lacked the vocabulary to translate my feelings into words. 我被这部小说所包含的巨大能量感到震惊。我无法用语言来表达我的感情（心情）。 4，make sth. long to short长话短说 5.I learned that summer that reading was not the innocent(简单的) pastime(消遣) I have assumed it to be., not a breezy, instantly forgettable escape in the hammock(吊床)，( though I’ ve enjoyed many of those too ). I discovered that a book, if it arrives at the right moment, in the proper season, will change the course of all that follows. 那年夏天，我懂得了读书不是我认为的简单的娱乐消遣，也不只是躺在吊床上，一阵风吹过就忘记的消遣。我发现如果在适宜的时间、合适的季节读一本书的话，他将能改变一个人以后的人生道路。 二、词组造句 1. on purpose 特意，故意 This is especially true here, and it was ~. (这一点在这里尤其准确，并且他是故意的) 2.think up 虚构，编造，想出 She has thought up a good idea. 她想出了一个好的主意。 His story was thought up. 他的故事是编出来的。 3. in the meantime 与此同时 助记：in advance 事前in the meantime 与此同时in place 适当地... In the meantime, what can you do? 在这期间您能做什么呢？ In the meantime, we may not know how it works, but we know that it works. 在此期间，我们不知道它是如何工作的，但我们知道，它的确在发挥作用。 4.as though 好像，仿佛 It sounds as though you enjoyed Great wall. 这听起来好像你喜欢长城。 5. plunge into 使陷入 He plunged the room into darkness by switching off the light. 他把灯一关，房

改写句子练习2标准答案

The effective sentences:(improve the sentences!) 1.She hopes to spend this holiday either in Shanghai or in Suzhou. 2.Showing/to show sincerity and to keep/keeping promises are the basic requirements of a real friend. 3.I want to know the space of this house and when it was built. I want to know how big this house is and when it was built. I want to know the space of this house and the building time of the house. 4.In the past ten years,Mr.Smith has been a waiter,a tour guide,and taught English. In the past ten years,Mr.Smith has been a waiter,a tour guide,and an English teacher. 5.They are sweeping the floor wearing masks. They are sweeping the floor by wearing masks. wearing masks,They are sweeping the floor. 6.the drivers are told to drive carefully on the radio. the drivers are told on the radio to drive carefully 7.I almost spent two hours on this exercises. I spent almost two hours on this exercises. 8.Checking carefully,a serious mistake was found in the design. Checking carefully,I found a serious mistake in the design.

用以下短语造句

M1 U1 一. 把下列短语填入每个句子的空白处（注意所填短语的形式变化）： add up (to) be concerned about go through set down a series of on purpose in order to according to get along with fall in love (with) join in have got to hide away face to face 1 We’ve chatted online for some time but we have never met ___________. 2 It is nearly 11 o’clock yet he is not back. His mother ____________ him. 3 The Lius ___________ hard times before liberation. 4 ____________ get a good mark I worked very hard before the exam. 5 I think the window was broken ___________ by someone. 6 You should ___________ the language points on the blackboard. They are useful. 7 They met at Tom’s party and later on ____________ with each other. 8 You can find ____________ English reading materials in the school library. 9 I am easy to be with and _____________my classmates pretty well. 10 They __________ in a small village so that they might not be found. 11 Which of the following statements is not right ____________ the above passage? 12 It’s getting dark. I ___________ be off now. 13 More than 1,000 workers ___________ the general strike last week. 14 All her earnings _____________ about 3,000 yuan per month. 二.用以下短语造句： 1.go through 2. no longer/ not… any longer 3. on purpose 4. calm… down 5. happen to 6. set down 7. wonder if 三. 翻译： 1.曾经有段时间，我对学习丧失了兴趣。（there was a time when…） 2. 这是我第一次和她交流。（It is/was the first time that …注意时态） 3.他昨天公园里遇到的是他的一个老朋友。（强调句） 4. 他是在知道真相之后才意识到错怪女儿了。（强调句） M 1 U 2 一. 把下列短语填入每个句子的空白处（注意所填短语的形式变化）： play a …role (in) because of come up such as even if play a …part (in) 1 Dujiangyan(都江堰) is still ___________in irrigation(灌溉) today. 2 That question ___________ at yesterday’s meeting. 3 Karl Marx could speak a few foreign languages, _________Russian and English. 4 You must ask for leave first __________ you have something very important. 5 The media _________ major ________ in influencing people’s opinion s. 6 _________ years of hard work she looked like a woman in her fifties. 二.用以下短语造句： 1.make (good/full) use of 2. play a(n) important role in 3. even if 4. believe it or not 5. such as 6. because of

英语造句

English sentence 1、(1)、able adj. 能 句子：We are able to live under the sea in the future. (2)、ability n. 能力 句子：Most school care for children of different abilities. (3)、enable v. 使。。。能 句子：This pass enables me to travel half-price on trains. 2、(1)、accurate adj. 精确的 句子：We must have the accurate calculation. (2)、accurately adv. 精确地 句子：His calculation is accurately. 3、(1)、act v. 扮演 句子：He act the interesting character.（2）、actor n. 演员 句子：He was a famous actor. (3)、actress n. 女演员 句子：She was a famous actress. (4)、active adj. 积极的 句子：He is an active boy. 4、add v. 加 句子：He adds a little sugar in the milk. 5、advantage n. 优势 句子：His advantage is fight. 6、age 年龄n. 句子：His age is 15. 7、amusing 娱人的adj. 句子：This story is amusing. 8、angry 生气的adj. 句子：He is angry. 9、America 美国n. 句子：He is in America. 10、appear 出现v. He appears in this place. 11. artist 艺术家n. He is an artist. 12. attract 吸引 He attracts the dog. 13. Australia 澳大利亚 He is in Australia. 14.base 基地 She is in the base now. 15.basket 篮子 His basket is nice. 16.beautiful 美丽的 She is very beautiful. 17.begin 开始 He begins writing. 18.black 黑色的 He is black. 19.bright 明亮的 His eyes are bright. 20.good 好的 He is good at basketball. 21.British 英国人 He is British. 22.building 建造物 The building is highest in this city 23.busy 忙的 He is busy now. 24.calculate 计算 He calculates this test well. 25.Canada 加拿大 He borns in Canada. 26.care 照顾 He cared she yesterday. 27.certain 无疑的 They are certain to succeed. 28.change 改变 He changes the system. 29.chemical 化学药品