Failing hips can be replaced, clinical depression controlled, cataracts removed in a 30-minute surgical procedure.
  →Failing hips can be replaced,(省略and)clinical depression(省略can be)controlled,(省略and)cataracts(省略can be)removed in a 30-minute surgical procedure.
  Do you remember all those years when scientists argued that smoking would kill us but the doubters insisted that we did not know for sure?
  →Do you remember all those years when scientists argued that smoking would kill us but the doubters insisted that we did not know(省略that smoking would kill us)for sure?
  Tom picked up a coin in the road and handed it to a policeman.
  →Tom picked up a coin in the road and(省略Tom)handed it to a policeman.
  并列连词and, but, as well as, or, or else, both…and…, neither…nor, either…or, not only…but (also), rather than, as…as等以及从属连词than可连接两个对等的词和对等的结构。
  【例句】He went shopping, bought some gifts and visited his old friend.
  【例句】We often go fishing as well as swimming.
  【例句】People find eating vegetables more healthy than fasting.
  【例句】My girlfriend is pleased with what I have said and all that I have done.


  When (he was) very young, he began to learn to play the guitar. 他很小的时候, 就开始学习弹吉他。
  While (I was) at college, I began to know him, a strange but able student. 我在上大学时就开始认识他, 一个奇怪但有能力的学生。
  Don’t come in until (you are) asked to. 不叫你请你不要进来。
  Whenever (it is) possible, you should come and help. 不管什么时候只要有可能你就该来帮忙。
  You should let us know the result as soon as(it is) possible. 你应该尽快让我们知道结果。  
  Send the goods now if (they are) ready. 货物如果准备好了, 现在就送过来。
  If (it is) necessary, ring me at home. 如有必要, 给我家里打电话。
  Come along with me if (it is) possible. 如果有可能和我一起去吧。
  If (it is) true, this will cause us a lot of trouble. 如果是真的, 这会给我们带来很多麻烦。
  There are few people nowadays, if (there are) any, who remember him.
  即使有人, 现在能记起他的也是寥寥无几。
  You should stay where you are, unless (you are) asked to leave. 你应该呆在你现在的地方不动, 除非叫你离开。  三、方式状语从句中的省略   
  as if / as though后加名词 /形容词 /副词 / 介词短语 / 现在分词 / 过去分词 / 不定式。
  She talked to the stranger as if (she were) absent-minded. 她和陌生人谈话似乎心不在焉。
  He opened the desk, as if (he was) in search of something important.
  The boy is running impatiently here and there as if (he is) searching for something lost on the sports ground. 这男孩很不耐心地在操场上到处跑着似乎在找所丢失的东西。
  The football player is rolling on the ground as if (he is) hurt badly in the leg. 足球运动员在操场上打着滚似乎他的腿伤得厉害。
  He moved his lips as if(he wanted) to speak. 他的嘴动着仿佛要说什么。

   Lay these books where possible you can find them easily. 把这些书放在你容易找到的地方。
  Put in articles wherever necessary in the following passages. 在下列文章中需要的地方填入冠词。
  He is a good man, though sometimes (he is) rather dull. 他是个好人, 尽管有时有点无聊。
  Even if (I am) invited to, I won’t go to such a bad lecture. 即使请我去, 我都不想听如此糟糕的报告。

  She has finished the work earlier than (it has been) expected. 她比预料的提前完成这项工作。
  She can play the piano just as wonderfully as you (do). 她钢琴弹得和你(弹的)一样好。
  1. Generally speaking,_____according to directions, the drug has no side effect.
  A. when taking B. when taken C. when to take D. when to be taken
  2. Though________money, his parents managed to send him to university.
  A. lacked B. lacking of C. lackingD. lacked in
  3. When_____, the museum will be open to the public next year.
  A. completedB. completing
  C. being completed D. to be completed
  4. The research is so designed that once________nothing can be done to change it.
  A. begins B. having begunC. beginning D. begun
  5. If_______the same treatment again, he’s sure to get well.
  A. giving B. give C. givenD. being given
  6. While building a tunnel through the mountain,________.
  A. an underground lake was discovered
  B. there was an underground lake discovered
  C. a lake was discovered underground
  D. the workers discovered an underground lake
  7. -Will you go and attend her party?
  -No,__________invited to.
  A. if B. whenC. for not D. even if
  8. The old tower must be saved,_______the cost.
  A. however B. whicheverC. whatever D. wherever
  9. You mustn’t touch it unless_______.
  A. asking to doB. asked toC. asking toD. to be asked
  10. If ______,the experiment will be successful.
  A. do carefullyB. did carefully
  C. carefully done D. doing carefully
  1. B2. C3. A4. D5. C6. D7. D8. C9. B10. C


一、关系代词作宾语时的省略当关系代词who, whom, which和that在定语从句中用作动词宾语或介词位于句末时的介词宾语时,可以省略。如:在定语从句中用作动词宾语或介词位于句末时的介词宾语时,可以省略。如:Is there anything (which) you wanted? 想要什么东西吗? Who is the man (that / who / whom) you were talking to? 刚才和你讲话的人是谁?

二、关系代词作表语时的省略当关系代词that在定语从句中用作表语时,可以省略。如:China is not the country (that) it was. 中国已不是过去的中国了。(that作表语)

三、关系代词作宾补时的省略当关系代词that在定语从句中用作宾语补足时,可以省略。如:I’m not the madman (that) you thought me. 我并不是你所认为的那个疯子。(that作宾语补语)

四、关系副词when的省略用作时间状语的关系副词when通常不能省略,但有一种特殊情况,即用于day, year, time等少数几个词后时可以省略(也可换成that)也可换成。如:That was the year (that) I first went abroad. 就是那一年我第一次出国了。I’ll never forget the day (that) we met. 我永远也忘不了我们见面的那一天。

五、关系副词where的省略用作地点状语的关系副词where通常不能省略,但有一种特殊情况,即用于place, somewhere, anywhere, everywhere, nowhere少数几个词后时可以省略(也可换成that)。如:This is the place (where) they met yesterday. 这就是他们昨天碰头的地方。Have you somewhere (that) I can lie down for an hour? 你有没有一个什么地方可以让我躺一个小时?

六、关系副词why的省略关系副词why通常只用于the reason后引导定语从句,且通常可换成that或for which,均可省略。如:That’s the reason (why, for which, that) he came.
Give me one reason (why) we should help you. 给我举出一个我们应当帮助你的理由。 absent, nothing couldn’t be done. 由于他缺席,什么事也干不成。



在let, make, have等使役动词后用作宾语补足语的不定式必须省略to。如:

My mother wouldn't let me go to the film. 我妈妈不会让我去看电影的。

I don't like milk, but mother made me drink it. 我不喜欢牛奶,可是母亲强迫我喝。

I would have him wait for me at the gate of the park. 我要他在公园门口等我。


1. 当使役动词用于被动语态时,要补上在主动语态中省略的to(主要是指make,let和have很少用于被动语态)。

2. force, oblige等虽然也表示“使”,但它们后用作宾语补足语的不定式必须带to。如:

He forced me to go with them. 他迫使我同他们一起去。

The police obliged him to leave. 警方强迫他离开。



I watched her get into the car. 我看着她上了车。

I saw the woman enter a bank. 我看见这个女人进了一家银行。

We often hear her sing this song. 我们经常听到她唱这首歌。

Did you notice her leave the house? 她离开屋子你注意到了吗?


1. 这里所说的感觉动词主要包括see, hear, observe, notice, feel, watch等。但是它们用于被动语态时,其后的不定式必须带to。如:

The woman was seen to enter a bank. 有人看见这个女人进了一家银行。

但是,用于以上句型的动词notice 和watch通常不用于被动语态。

2. 类似地,动词look at和listen to后用作宾语补足语的不定式也不带to。如:

We listened to the old man tell his story. 我们听这位老人讲述他的经历。

3. 若动词feel后用作宾语补足语的不定式为 to be,则要带 to(其他情况不带 to)。如:

They felt the plan to be unwise. 他们认为这个计划不明智。

4. 若不定式为完成式,通常应带 to。如:

I noticed her to have come early. 我注意到她来得很早。



Can I help (to) carry this heavy box? 我可以帮忙扛这个重箱子吗?

Mother helped me (to) do my homework. 妈妈帮助我做作业。


1. 当 help 之后接一个较长的名词词组作宾语或当其中的不定式所表示的动作主语不直接参加时,不定式通常带to。如:

Help the little boys at the back of the hall to carry the chairs out. 请帮大厅后面那些小男孩把椅子搬出去。

These tablets will help you to sleep. 这些药片将对你的睡眠有帮助。

2. 在当help用于被动语态时,不定式前的to不能省略。如:

The boy was helped by a woman to collect his scattered coins. 那男孩由一个妇女帮他捡拾散乱一地的钱币。

四、why (not)…后省略to的情况
在why (not)…?之后的不定式不能带to。如:

Why go with him? 为什么要同他一起去?

Why not ask the teacher? 为什么不去问问老师?

Why not try to expand your story into a novel? 你怎么不把你的故事扩展成小说呢?



1. 若 know 为现在式,该结构中的不定式只限于 to be,且其中的to不能省略。如:

I know him to be ill. 我知道他病了。

We knew her to be honest. 我们知道她是诚实的。

2. 若know为完成式或过去式,则该结构中的不定式可以用除 to be外的其他动词,且此时其中的to可以省留。如:

I never knew him (to) do such a thing. 我从未听说他会干那种事。

We've never known him (to) tell a lie. 我们从未听说他撒过谎。

I’ve never known it (to) snow in July before. 我从未听说过有七月下雪的事。


六、介词except / but后省略to的情况

用作介词except, but宾语的不定式有时带to,有时不带to。其大致原则是:若其前出现了动词 do,其后的不定式通常不带 to;若其前没有出现动词 do,则其后的不定式通常带 to。如:

I had no choice but to wait. 除了等,我没有别的选择。

He wanted nothing but to stay there. 他只想留在那儿。

It had no effect except to make him angry. 除惹他生气外,没产生任何效果。

She can do everything except cook. 除了做饭之外她什么都会。



All you do now is (to) complete the form. 你现在要做的只是把这张表填好。

The only thing to do now is (to) go on. 前进是现在唯一的出路。

What I'll do is (to) tell her the truth. 我要做的就是告诉她真相。



He told me to stay there and wait for him. 他叫我在那儿等他。

I'm really puzzled what to think or say. 我真不知该怎么想怎么说。

It is easier to persuade people than (to) force them. 说服人容易,强迫人难。


To try and fail is better than not to try at all. 尝试而失败总比不尝试好。



I shall go if I want to. 如果我想去就去。

"Don't be late." "I'll try not to." “不要来晚了。”“我尽量不来晚。”

Don't go till I tell you to. 等我叫你走你再走。


1. 若被省略的不定式为to be短语,则通常应保留to be。如:

He is not the man he used to be. 他已不是原来的那个样子了。

2. 有时省略不定式时,同时也可省略to。如:

She may go if she likes (to). 她想去就可以去。