不定式是歷次大學英語四級考試必考的內容。不定式在句子中可做主語、賓語、表語、定語、狀語和賓語補語。
1)不定式做主語一般表示具體的某次動作。
【例如】To complete the 30storied building in one year was
quite a difficult task.
To do that implies taking responsibility.
當主語較長，謂語較短時，常用it做形式主語，而將不定式放到謂語的后面。
【例如】It is important for modern young people to master at least two foreign languages.
It做形式主語，不定式放在謂語動詞之后常用
于下列結構中：
a) It is＋形容詞(easy, important, difficult, foolish, inconvenient, unnecessary, right, wrong...)＋( for/of sb.)＋不定式
【例如】It is essential to reserve a table in advance of Christmas Eve. hard to put my hopessintoswords.
It is not easy to catch fish with your hands only.
It is important for us young people to learn English and master it.
b) It is＋名詞(a pleasure, a pity, a pleasant thing, one’s duty, an honor, a shame, a crime, no easy job...)＋不定式
It is a sheer waste of time to read that kind of trash.
It is a pity to have to go without her.
It is a glorious death to die for the people.
c) It takes (sb.) some time (hours, months, days, a lot of time, patience...)＋不定式
It takes me three hours to learn English each day.
It took them half the night to get home in the snow.
2)不定式作表語不定式作表語常表示將來的動作，主語常常是表示意向、打算、計劃的詞，如wish, idea, task, purpose, duty, job等。
【例如】The most important thing for one’s health is to have plenty of exercise.
My chief purpose has been to point out the difficulties of the matter.
The purpose of the organization is to greet all new comers to the city and to provide them with any necessary
information. What I wanted was to get the work done as quickly as possible.
3)不定式作賓語不定式常在下列動詞后面作賓語：
afford,agree,apply,arrange,ask,attempt,beg,begin,care, choose,claim,consent,demand,decide,desire,determine,
expect,fail,hope,hesitate,hate,intend,learn,like,manage,mean,neglect,offer,plan,preparepretend,promise,refuse,resolve,seek,tend,threaten,want等。
【例如】I like to go out for walks in the warm sunshine in spring.
My mother hates to move from place to place, for she feels tired.I decide to work hard and get doctor’s degree.
The room is designed to be my study,but now it has to be used as a bedroom for the children.
She failed to finish the assignment in time, and she was worried about it.
There is a man at the reception desk who seems very angry and I think he means( )trouble. (CET-4 1997, 1)
A) making B) to make C) to have made D)shavingsmade
mean后面一般加不定式，所以A和D可以排除。根據句意，他看起來非常生氣，他想找麻煩，不定式的動作還沒有實施， 應用一般式，因此答案為B。不定式作賓語還常用在下面結構中；主語＋動詞＋it＋形容詞＋不定式。
【例如】 We found it impossible to get everything ready in time.I think it important to learn English well in college.使用這種句型的常見動詞有：believe, consider, declare, feel,find, guess, imagine, prove, realize, suppose, think,等。
4)“whword＋不定式”結構不定式前加一個疑問代詞(what,which, who, whom, whose)或疑問副詞(where, when, how, why)，以及連詞whether構成特殊的不定式短語，其作用相當于一個從句，這樣的不定式短語常在某些動詞后面作賓語。常見的可以接這種不定式短語的動詞有：know, see, decide, tell,ask,consider,discover,explain,findout,forget,guess,hear,imagine,inquire,learn,observe,perceive,remember,think,understand,wonder等。
