疑问词+不定式动词

　　英语有个很有用的结构，就是：疑问词+不定式动词（question word + to-infinitive）。

　　疑问词是疑问代词“who, whom, what, which, whose”和疑问副词“when, where, how, why ”。此外，连接词“whether”也适用。

　　“疑问词+不定式动词”结构有何功用呢？其主要功用有下列五种：

　　⑴当主语，如：
● When to hold the meeting has not yet been decided.
● Where to live is a problem.
● How to cope with the rising cost of living becomes a daily discussion topic.

　　⑵当宾语，如：
● We must know what to say at a meeting.
● He could not tell whom to trust.
● Do you know how to play bridge?

　　⑶当补足语，如：
● The problem is where to find the financial aid.
● The question is who to elect.

　　⑷当名词同位语，如：
● Tom had no idea which book to read first.
● Do you have a rough impression how to do it?

　　⑸当宾语补足语，如：
● Jim is not sure whose to choose.
● Mary and John are not certain whether to get married or not.

　　适用于“疑问词+不定式动词”的动词包括：“know, see, decide, tell, ask, consider, discover, explain, forget, guess, hear, imagine, inquire, learn, remember, think, wonder, understand”等。

　　有点值得特别注意的是：当这结构当宾语时，它的作用等于名词分句，例如：
● I could not decide which dictonary to buy. / I could not decide which dictionary I should buy.
● Jack did not know where to find such a good teacher./ Jack did not know where he could find such a good teacher.

　　有些动词，如“ask, show, tell, advise, inform, teach”等，可以先有个宾语，然后才接着加上适当的“疑问词+不定式动词” 结构。例如：
● The chief technician showed the apprentice how to repair the machine.
● Have you told him where to get the application form?

　　综上所述，可见“疑问词+不定式动词”结构是个形象清新，既容易用又不容易出错的特别结构，可以多多运用。

“疑问词+不定式”结构小结

2010-04-06 21:25

 “疑问词 + 动词不定式”构成的不定式短语是本话题的语法“主角”。想了解它的更多知识，请关注以下三个看点：

    第一看点： “疑问词 + 动词不定式”的个性

    此结构中疑问词包括疑问代词who, what, which以及疑问副词when, where, how等（不与why连用）。这些“疑问词 + 动词不定式”结构经常放在forget, find out, discuss, decide, tell, teach, know, learn, wonder, remember等动词之后作宾语。如：

    I don't know what to do. 我不知道该做什么。

    He told me how to answer all the questions in English. 他告诉我怎样用英语回答所有的问题。

    第二看点：“疑问词 + 动词不定式”的功用

    “疑问词 + 动词不定式”结构在句子中可以用作宾语、主语和表语等。如：

    How to do it is a question. 如何做是个问题。（用作主语）

    He knows what to do and what not to do. 他知道该做什么，不该做什么。（用作动词宾语）

    The question is how to put it. 问题是应该把它如何放才好。（用作表语）

    第三看点：“疑问词 + 动词不定式”的转换

    “疑问词 + 动词不定式”结构相当于一个名词性从句，常常可用同等成分的从句代替。改写后的句子需要在疑问词后加上相对应的主语，并要注意主谓语单复数的一致性。如：

    The question is where to put it. →The question is where we should put it. 问题是应该把它放在哪里才好。

    一些动词如tell, know, ask, show, teach, find (out), forget等都可接“疑问代（副）词（why除外） + 不定式”作宾语，充当简单句，其意义相当于一个宾语从句。这种句式可转化为含宾语从句的复合句。当然在句型转换中，并非所有的宾语从句都能转换为“疑问词 + 不定式”结构。

    看一下下面的情况：

    主句的谓语动词是decide, hope, wish, know, forget等时，句子中的“疑问词 + 动词不定式”结构可转化为宾语从句。此时从句的主语和主句的主语相同。如：

    We can't decide when to start. →We can't decide when we should start.

    We don't know what to do next. →We don't know what we should do next.

    注： 主句的谓语动词是tell, ask, teach, show等，并且从句主语一致时，宾语从句可转化为“疑问词 + 不定式”结构。如：

    Please tell us where we show our tickets.→Please tell us where to show our tickets