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。