疑问词+不定式-讲解及各题型练习

英语语法- 疑问词+不定式一、基本用法说明疑问词what, which, who, when, where, how及连接副词whether与不定式连用而形成一个短语，这个短语相当于一个名词，可在句中做句子的主语、宾语或表语等。如：1. 作主语。如：What to do is not decided yet. 该做什么还没有确定。How to begin is more difficult than where to stop. 如何开始比到哪里停止还困难。2. 作宾语。如：Do you know when to start? 你知道什么时候开始吗？I showed her which button to press. 我告诉她应该按哪一个按钮。有时还可用于介词后作宾语。如：I found a book on how to avoid having a heart attack. 我找到一本书谈如何避免心脏病复发。She was worried about how to fill her leisure time. 她为如何打发她的闲暇时间而发愁。3. 作表语。如：The question is how to carry out the plan. 问题是怎样执行这个计划。The difficulty was how to cross the river. 困难在于如何过河。二、“疑问词+不定式(短语)”是一个很有用的结构，它的作用相当于一个名词性从句，通常在某些动词(如tell, know, imagine, learn, decided, forget, remember, consider, understand等)后面做宾语，有时也用作主语、表语、同位语等。如：He didnt know how to answer her. 他不知道该怎样回答她。When to start has not been decided. 何时动身尚未决定。I dont know who to ask advice from. 我不知道应向谁征求意见。Would you please advise me which to buy? 你能否告诉我该买哪一个才好?Please explain (to me) where to begin and how to do it. 请 (给我)解释该从哪里开始及该怎么做。They exchanged views on the question of whom to elect. 他们就该选谁的问题交换了意见。注意：按英语习惯，疑问词why后面通常不接不定式。但在以why或why not 开头的省略型疑问句中，其后可跟不带to 的不定式。如：Why get upset just because you got a bad mark? 何必因为没有考好就想不开呢?Youre looking tired. Why not take a holiday? 你一脸倦容，怎么不休假呢?三、五个易错点易错一：是否用于疑问词why之后按英语习惯，有一个疑问词不能用于“疑问词+不定式”结构，就是why。如：我不明白为什么马上就走。误：I dont know why to leave at once.正：I dont know why we must leave at once.why后面可以跟不带to的动词不定式(即动词原形)，用以表示某动作是不必要的或无意义的。如： Why pay more at other shops? We have the best value. 为什么花更多的钱到其他商店去买呢? 我们这里最物美价廉。另，why后面不带to的动词不定式有时也可能是否定的，该结构主要用来提出建议。如：Youre looking tired. Why not take a holiday? 你一脸倦容，怎么不休假呢?易错二：与动词think连用有何特别之处“疑问词+不定式”结构，通常不用于动词think的现在式和过去式之后，但可以用于think的其他形式之后（如进行式）。如：Im thinking what to do next. 我在想接下来要做什么。另外，“疑问词+不定式”结构也通常用于还有助动词的think之后。如：She couldnt think what to say. 她想不出该说什么。She couldnt think what to give the children for Christmas. 她想不出圣诞节该送孩子们什么礼物。易错三：与动词know连用要注意什么当要表示知道如何做某事，know之后不能直接跟动词不定式作宾语，此时可改用know how to结构。如：我会做西班牙式的摊鸡蛋。误：I know to make Spanish omelettes.正：I know how to make Spanish omelettes.易错四：与某些只接动名词作宾语的动词连用有些动词可以接“疑问词+不定式”作宾语，但通常不直接跟不定式作宾语。这类动词主要有consider (考虑), discover (发现), discuss (讨论), explain (说明), find (out) (查到), know (知道), observe (观察), suggest (提议), wonder (怀疑), understand (了解)等。如：Have you considered how to get there? 你是否考虑过如何到那儿去?Our teacher explained how to use the machine. 老师向我们说明如何使用这台机器。We discussed what to do and where we should go. 我们讨论了该怎么办及到哪里去。你能说明一下蛋糕的做法吗?误：Can you explain to make a cake?正：Can you explain how to make a cake易错五：which to do 的两种用法要注意“which+不定式”结构，其中的which有时是疑问词。如：I cant decide which to choose. 我不能决定选哪个好。Did you ask her which to buy? 你问没问她该买哪一个?有时可能是关系代词，相当于一个省略的定语从句，此时主要用于介词后作宾语。如：She must have time in which to grow calm. 她必须有冷静下来的时间。Allow me one minute in which to change my costumes. 给我一点时间来卸装。这两句中的which to也可改为定语从句：She must have time in which she can grow calm.Allow me one minute in which I can change my costumes.巩 固 练 习一选择1. Mr. Wu advised us _to choose in this shop.A. which B. from which C. what D. how 2. The students do not know _this math problem.A. how to deal with B. what to do C. how to do with D. what to deal with3. Xiao Ming has explained _ late for class to his teacher.A. why to be B. why he was C. that he was D. why be4. Are you sure_?A. how to work it out B. how to work out it C. what to work out it D. what to work it out5. He didnt think _ was easy.A. who to choose B. choosing a person C. chose a person6. He did not say _ for help.A. whose to ask B. whom to ask C. which to ask D. what to ask 二、填空1. _ is a question该怎样做倒是一个问题。(作主语)2. I really dont know _我实在不知道该写些什么.（作动词宾语）3. We must first solve the problem of_我们必须首先解决为谁服务的问题.（作介词宾语） 4. The question is _问题是该把它放在哪儿才好.（作表语）5. I asked him_我问他如何学习英语.（作宾语补足语）6. The teacher told the students _ the experiment老师教学生如何做实验。 7. The young woman doesnt know_ 那位年轻女子不知道怎么办. 8. He tells me_ all the questions in English他告诉我怎样用英语回答所有的问题. 9. _ is unknown何时动身还不知道.10. I forgot _ 我忘了该怎么办.11. I can tell you _ 我可以告诉你哪里可以买到此书.Key: 1. How to do it 2. what to write about 3. whom to serve 4. where to put it 5. how to learn English 6. how to do 7. what to do 8. how to answer 9. when to start 10. what to do 11. Where to buy（get）this book三、句子改写，改成“疑问词不定式”结构1. How we should do it is a question 2. I really dont know what I should write about 3. We must first solve the problem of whom we should serve 4. The question is where we should put it 5. I asked him how we should learn English四、用“疑问词不定式”完成下列句子.1. How we should do i