1．do
do用来代替动词或动词加其他成分。
I know you better than he does. 我比他更了解你。(he does等于he knows you)
--- Have you finished your work
--- Yes, I did yesterday. (did替代finished my work)
5．主句和从句中可同时省略一些成分。
The sooner (this is done), the better (it will be). 越快越好。
(If you take) No pains, (you will make) no gains. (谚)不劳则无获。
C． 使用替代词的省略
我们在省略句子某些成分时，有时还必须加上适当的替代词，如do, so, one等，以保持句子意思的完整。
4．在比较从句中通常把和主句重复的部分省掉。
①省略谓语的全部
James enjoys the theatre more than Susan. 詹姆斯比苏姆更喜欢戏剧。(Susan后省略了enjoys the theatre)
Tom has as many books as Jack. 汤姆有跟杰克一样多的书。(Jack后省略了has many books)
②省略主语和谓语的一部分
Brown speaks French as fluently as English. 布朗说法语和英语一样流利。(as后省略了he speaks)
She was more angry than frightened. 与其说她害怕，倒不如说她生气。(than后省略了She was)
③省略表语部分
Mrs White is not so young as she looks. 怀特夫人没有看上去那样年轻。(looks后省略了young)
The situation is much more delicate than it seems. 情况要比表面上看起来微妙得多。(seems后省略了delicate)
④省略主语和谓语的大部分，保留状语
He is working harder than before. 他现在工作比过去努力多了。(than后省略了he worked hard)
There are as many students in our school as in their school. 我们学校的学生和他们学校的学生一样多。(as后省略了there are many students)
⑤省略主语
He drank a little more than was good for him. 他喝酒稍有一点过量。(than后省略了it)
⑥省略宾语
You spent more money than I had expected. 你花掉的钱比我预料的多。(expected后省略了that you should spend)
I was able to borrow as many books as (what) I asked for. 我想要的许多书如数借到。
⑦省略从句的全部
You are getting slimmer. 你越来越苗条了。(slimmer后省略了than you were before)
It is not only blind men who make such stupid mistakes. People who can see sometimes act just as foolishly. 不仅仅只是瞎子才犯如此愚蠢的错误。有时候，眼睛看得见的人也做出同样的蠢事。(foolishly后省略了as blind men act)
注意：
在这类句子中，被省略的部分大多数是不表示出来的。如果把省略部分补上，反而不合乎习惯。
He is taller than I am. 他比我高。(am之后省略tall，补上不合习惯)
3．在一些状语从句中，如果谓语动词是be，主语又和主句的主语一致，或者主语是it，常常可以把从句中的主语和be省略掉。
①以when, while, once, until等连词引导的时间状语从句
When (you are) in Rome do as Rome does. 入国问禁，入乡随俗。
Whenever (it is) possible, you should speak English as much as you can. 在任何可能的时间，你应多讲英语。(省略的主语it并不和主句的主语一致)
Please come as soon as (it is) possible. 请尽快来。
由连词before和after引导的时间状语从句，如省略了主语和be之后，before和after就成了介词。
The old machine must be checked before it is used. 这台旧机器在使用前必须检查。
[误]The old machine must be checked before used. (动词的-ed形式不可做介词的宾语)
[正]The old machine must be checked before being used.
He told me the truth after he was asked three times. 问了他三遍他才告诉我真相。
[误]He told me the truth after asked three times.
[正]He told me the truth after being asked three times.
②以as if, as though等连词引导的方式状语从句
She lay there, as if (she was) dead. 她躺在那儿，好像死了。(省略的主语和主句的主语一致)
He opened his lips as if (he were going) to say something. 他张开嘴唇，好像要说什么话似的。
③以if, unless等连词引导的条件状语从句
We shall start at eight, if (it is) convenient. 如果方便的话，我们八点钟出发。
Correct the mistakes in the following sentences, if (there are) any. 如果下面句子中有错，请加以改正。
English words are easily forgotten unless (they are) constantly repeated. 英语单词不经常重复是很容易忘记的。
④以even if, even though, though, although, whether等连词引导的让步状语从句
Frost is possible, though (it is) not probable, even at the end of May. 甚至在五月底下霜也是可能的，虽然可能性不太大。
Whether (it is) difficult or not, we will try our best to complete the task. 不管任务是否艰巨，我们都要尽力去完成。
Whatever the cause (may be), the result is certain. 不论原因是什么，结果是确定的。
Though (he is) young, he knows a lot. 他虽然年轻但懂得很多。
提示：
在这类从句中，如果be是助动词，后面跟着现在分词或过去分词，只要主语和从句中的主语相同，也可以把从句中的主语和助动词be省略掉。
He hurt his leg while (he was) riding a horse. 他在骑马时伤了腿。
When (you are) cycling, don't forget the traffic lights. 骑车时，不要忘记看红绿灯。
Once (it is) seen, it can never be forgotten. 一旦看见，就永远不会忘记。
If (it is) burnt, rubber can give off a poisonous gas. 橡胶如果燃烧起来，会发出有毒气体。
2．省略整个主句或主句的一部分(回答问题时常用)。
(It is a ) Pity he's failed. 很遗憾，他失败了。
If he says he'll come, he will (come). 如果他说来，他就一定会来。
What (will happen) if it's raining 如果天下雨怎么办？
- Where is it 那东西在哪里？
-(It is) Where you left it. 就在你放的地方。
- How are you getting on with your English 你的英语学得怎么样？
- (I'm) Not (getting on) so well as I expected.没有我预计的那样好。
- Will you go abroad soon 你很快要出国吗？
- (I'll) Not (go abroad) until I graduate from the college next summer. 要到明年夏天大学毕业后才走。
1．省略主句的句首部分。
(I'm) Sorry I couldn't go. 很抱歉，我不能去。
(Is there) Nothing more you want to say 你没什么要补充吗？
3．前后两个分句都出现省略。
They can (pay the full fee) and (they) should pay the full fee. 他们能够也应该支付全部费用。
I'll fly to (Guangzhou), but (I'll) drive back from Guangzhou. 我将飞往广州，但开车回来。
C．复合句中的省略
在主从复合句中，省略的现象是很普遍的。
2．省略出现在前一分句。
We can (win tomorrow's match), and certainly will, win tomorrow's match. 我们能够，而且一定会在明天的比赛中获胜。(前一分句省略谓语+宾语)
I wished (to find him), yet feared to find him. 我又想找到他，又怕找到他。
1．省略出现在后一分句。
John likes collecting stamps but (John) hates listening to music. 约翰喜欢集邮但不喜欢听音乐。(省略主语)
Some books are to be tasted, others (are) to be swallowed, and some few (are) to be chewed and digested. 有些书是应当尝尝滋味的，有些书是应当吞食下去的，有少数书是应当咀嚼和消化的。(省略谓语)
I have been to Beijing and (I have) seen the Great Wall. 我到过北京，见到了万里长城。(省略主语+助动词)
I asked him to see the film, but he didn't want to (see the film). 我请他去看电影，但他不想去。(省略作宾语的不定式)
为了避免重复，不定式可以省去与句子前面重复的动词原形，但不定式符号to必须保留(详见第5章)。
-Will you join in the game 你愿意参加这项活动吗？
-I'd be glad to (join in the game). 我很乐意参加。
I didn't want to go there, but I had to (go there). 我不想去那里，但没办法。
2．不依赖于上下文的省略。
All aboard! 请上船。(=All go aboard. 省略谓语)
What exciting news! 多么令人激动的消息啊！(= What exciting news it is! 省略主语+谓语)
Sounds like a good idea. 听上去是个好主意。(= It sounds like a good idea. 省略主语)
Everybody appears well prepared. 看起来大家都准备好了。(=Everybody appears to be well prepared. 省略不定式to be)
B． 并列句中的省略
并列句中如果前后分句有相同的部分，常常可以省略掉，以避免重复。通常被省略的可以是主语、谓语、谓语动词、宾语或其它成分，或句子成分的一部分。