简单句与复合句的互换
把一个简单句转换成一个复合句，一般是将一个短语变为一个从句。相反，复合句转换为简单句时要把一个从句变为一个短语。
1.The foreigners want to know how they can learn to do Chinese Kongfu well.→The foreigners want to know how to learn to do Chinese Kongfu well.【解析】含宾语从句的复合句变为简单句，可以把宾语从句改为"疑问词+不定式"的结构或者改为"主语+谓语+宾语+宾补"这种结构；简单句变复合句，一般是把宾语扩大为宾语从句，其宾语从句应该用将来时或"情态动词+动词原形"的形式。
2. She was so weak that she couldn't take care of her baby.→She was too weak to take care of her baby.
3. The ice on the lak e was so thin that people couldn't skate on it.→The ice on the lake was not thick enough for people to skate on.【解析】当so...that从句是否定句，其主语与主句主语相同，可用句型too...to do sth.替换；当so...that从句是否定句，其主语与主句主语不相同，可用句型too...for sb. to do sth.替换；当so...that从句是肯定句，其主语与主句主语相同时，可用...enough to do sth.替换；当so...that从句是肯定句，其主语与主句主语不相同时，可用...enough for sb. to do sth.替换。
4.Be brave,or you'll lose your chance.→If you aren't brave,you'll lose your chance.
5. Come on, or we'll miss the early bus.→If we don't hurry, we'll miss the early bus.【解析】"祈使句+or+简单句"可转换为"if引导的否定的条件句+主句"的句型；"祈使句+and+简单句"可转换为"if引导的肯定的条件句+主句"的句型。
6. She seems to be worried now.→It seems that she is worried now.【解析】seem是关于内心活动的用语，含有心中所想象的意思在内。seem后接动词不定式，也常用It seems that结构。简单句变为复合句应特别注意它们之间的同义可换性。
II.简单句与简单句的转换简单句本身可以通过对句子成分(包括主语、谓语、宾语、状语和定语)或句型自身的调整来表达相同或相近的意思。常见的转换方法有：
①"词与词的转换"(如：
反义词的转换、同义词的转换、代词的转换、词性的转换)；②"词与短语的转换"(of属格与's属格的转换、时间表达的转换等)；③"句式与句式的转换"(如：
How old is (are)...?与What is sb.'s age?的转换、How do you like...?与What do you think of... ?的转换、"动词+ sb. + sth."与"动词+ sth. +介词+ sb."的转换等)。
7.We spent twenty minutes cleaning the room yesterday.→It took us twenty minutes to clean the room yesterday.
8.The motorbike cost him 7,000yuan last year.→He paid /spent 7,000yuan for /on (buying) the motorbike last year.【解析】spend与take都可以表示"做某事花某人多少时间或金钱"。spend的主语用某人表示；take的主语用it。即"(Somebody)spend some time(in) doing sth. / on sth."这一句型可换成"It takes / took somebody some time to do sth."句型。两个句型都可表示"某人花若干时间做某事"。但在转换时，应注意语序的变化，尤其是前一个句型中(in)doing或on sth.，在后一个句型中应改为to do sth.。"spend...doingsth."相当于pay...for,它们之间可转换使用。
9.Jane says science isn't so interesting as music to her.→Jane says science is less interesting than music to her.
10.She rides a bicycle more carefully than anyone else in her class.→She is the most careful bicycle rider in her class.【解析】常见的比较等级之间的转换有：
①"not so / as+原级+ as"可改为"比较级+ than"；②"not so / as+原级+as"可改为"less+原级(多音节词)+than"；③"最高级+of/in短语"可改为"比较级+thany other+复数名词/than any of the others /anyone else / anything else"；④"like...better (than)"可改为"prefer...(to)"。
11. The exhibiti on of children's art began a few days ago.→The exhibition of children's art has been on for a few days.
12. My grandpa joined the Party thirty years ago.→My grandpa has been in the Party for thirty years.
13. Sam's grandfather died 10 years ago.→Sam's grandfather has been dead for 10 years.
【解析】含一般过去时与现在完成时句式之间的转换是很常用的。在现在完成时中，延续性动词与表示一段时间的状语连用，瞬间动词不能。但是，可以用别的方式来表达：
14.You must throw the broken pottery away at once.→The broken pottery must be thrown away at once.
15. Every one should give back his or her library books on time.→Library books should be returned on time.
首先把主动句的宾语变为被动句的主语，再把谓语动词变为被动语态，最后加上介词by的宾语(有时可省略)；②被动句变为主动句的方法是：
先把被动句中by的宾语变为主动句的主语(如被动句中省略了介词by及其宾语，一般可以用we,you,they等作主语)，再把谓语动词改为主动语态(即把be 去掉)，最后把被动句的主语改为主动句的宾语，主动句的时态与被动句中be
的时态一致；③在let, make, hear, see, watch等后的动词不定式在主动语态中不带to，变为被动语态时，要加上to；④双宾语动词结构变为被动语态，则应在间接宾语前加上相应的介词to或for。
如：
Li Lei was given a bike by Mr Wang.→Mr Wang gave a bike to Li Lei.
III.二合并一成简单句有时为了使句子结构更加紧凑，语言更加生动，我们可以把两个或两个以上的简单句合并为简单句，这样，句子意思上的联系显得更密切。
17. Lucy can't sing the English song "Yesterday Once More". And Lily can't sing it, either.→Neither Lucy nor Lily can sing the English song "Yesterday Once More".
18. This store sells men's shoes, and it also sells men's clothes.→This store sells not only men's shoes but also men's clothes.【解析】两个意义相关的简单句合并为一个简单句。常见的方式有三类：
①用both...and, not only...but also, either...or, neither...nor, not...but等连接词合并。由not only...but also, either...or, neither...nor等连接的并列主语，通常遵循就近原则，即谓语需根据后面的名词(词组)的单复数而定；②用too...to, enough to等含不定式结构合并；③用分词短语合并。
IV.二合并一成复合句由两个简单句合并成一个复合句，多把一个分句转换成一个从句。如：
19. "Did you sleep well last night?" David asked her.→David asked her if / whether she slept well last night.
20.I won't go with my brother,he thinks.→He doesn't think I will go with my brother.
21. Where does he live? I don't know.→I don't know where he lives.【解析】构成宾语从句应注意三点：
①宾语从句的引导词是否缺少或用错；②宾语从句语序是否是陈述句的语序；③宾语从句的时态是否与主句谓语动词的时态相呼应。
【测试】按要求改写下列句子。每空限填一词。
1.There is a strong wind today.It's very ____today.
2.What's the weather like in America?________ the weather in America?
3. We must keep the noise under 50 dbs (分贝) here.The noise must ____ ____ under 50 dbs here.
4. Wu Dong joined the Leaguethree years ago.Wu Dong has ____ in the League ____ three years.
5. Ididn't know what I should say.I didn't know what ____ ____.
6. Doesthe shop close at six every day?Do you know?Do you know ____the shop ____at six every day?
7.Lucy is the tallest girl in her class.Lucy is ____ than ____ ____ girls in her class.
8. Tom is in the football team.Jim is in the football team, too.____ Tom ____ Jim ____ on the footballteam.
9.John will go to bed after he finishes his homework.John ________to bed
____he finishes his homework.
10.He was so happy that he couldn't say a word when he was told the news.He was ____ happy ____ say a word when he was told the news.Key:
1. windy
2. How is / How about / What about
3. be kept
4. been; for
5. to say
6. if; closes
7. taller; any other
8. Both; and; are
9. won't go;until
10. too; to。
编辑本段误区提醒
不同的动词使用的句型也不尽一样，因此在学习动词时，应掌握动词的类型。以get 为例：
He's getting angry. (S V P)He got through the window. (S V M)You'll get a surprise. (S V O)He got his shoes and socks wet. (S V O C)He got himself into trouble. (S V OM)He got her a splendid present. (S V o O)在句子中词类和词的位置也影响句子的句型和意思:
I found the book easily.我很容易地找到了这本书。（S V O M）I found the book easy.我觉得这本书很容易。（S V O C）I have to do something.我得做点事。I have something to do.我有点事做。