1. （1）“wh- +不定式”结构不定式前加一个疑问代词(what, which, who, whom, whose)或疑问副词(where, when, how, why)，以及连词whether构成特殊的不定式短语，其作用相当于一个从句，这样的不定式短语常在某些动词后面作宾语。常见的可以接这种动词不定式短语的动词有：know, see, decide, tell, ask, consider, discover, explain, findout, forget, guess, hear, imagine, inquire, learn, observe, perceive, remember, think, understand, wonder等。例如：
① I couldn’t decide which book to choose. I can tell youswheresto get this book.They found it hard to decide whether to go swimming next Sunday or to visit Aunt Sally in New Year.
② When to start the program remains undecided. The question is how to put the plansintospractice.
（1）不定式作状语表示目的。或用于so as和in order之后，来强调这种目的。例如：
① To learn a foreign language well, you must make painstaking efforts.
② Mother saved every cent she could spare to pay for my schooling.We must develop science and technology at high speed so as to raise scientific and cultural level of our country.
③ Insgroupsto get a high mark in Band 4, he did a lot of exercises both in grammar and reading comprehension.
（2）动词不定式表示结果，特别是在so...as to, such...as to, only to...以及too...to等结构中的不定式表示结果。例如：
① I rushed to the station as fast as I could, only to find the train already gone.
② She left her hometown with her beloved man, never to return.No one is too old to learn.
③ Would you be so kind as to carry the luggage for me?
（3）动词不定式常用来修饰形容词，构成下列词组：be able to, be afraid to, be apt to, be bound to, be certain to, be easy to, be eager to, be fit to, be likely to, be ready to, be sure to, be unable to, be unwilling to, be willing to等。例如：
① Chinese team is bound to win the World Cup.
② It is likely to rain today, for it is very cloudy.
③ I am willing to help you with your homework, for we are friends.
3. 动词不定式作宾语补语不定式常跟在下列动词之后作宾语补语：ask, advise, allow, beg, cause, compel, command, enable, encourage, expect, feel, force, find, hear, have, inform, invite, let, make, mean, notice, order, permit, persuade, remind, require, request, teach, tell, urge, watch, warn, watch等。例如：
① Because of the complexity of the modern equipments, most offices require secretaries to have specified training.
② He asked you to call him at ten o’clock.