一. 动词不定式做主语

It's adj/noun (for sb) to do

动词不定式做主语，it为形式主语

It's a pity for you to drop out of school.

= For you, to drop out of school is a pity.

真遗憾，你竟然辍学了。

It's a pleasure for me to be your guest.

= For me, to be your guest is a pleasure.

很荣幸得到你的邀请。

It's a good plan for you to make more friendships.

= For you to make more friendships is a good plan.

广交朋友是个好打算。

It's a good idea for you to eat less fried food

= For you to eat less fried food is a good idea.

你少吃点油炸食品是好想法。

It was difficult to answer the question.

这问题很难回答。

It looked impossible for me to finish on time.

我似乎不可能按时完成了。

It was stupid of him to press the emergency button.

他按了紧急按钮，这真愚蠢。

如果形容词既可以修饰句子中的人，也可以修饰句子中的不定式，人前要用“of”

注意：有的句子与这种句型形式相同，但句子成分不同：

A. "It" 是真正主语，相当于 "this" or "that":

It's a suggestion for you to study a lot.

建议你多学习。

It's an order for you to do your homework.

做你的作业，这是命令。

It's a recommendation for you to get a university degree.

建议你上大学拿学位。

B. "It" 指代时间，做主语:

It's time for you to get a real job. = Now is the time for you to get a real job.

二. 动词不定式做宾语

1. 谓语动词＋动词不定式（多数动词属于此类动词）

Some students hate to study English.

有些学生不喜欢研读英语。

You need to study in a quiet place.

你必须在一个安定的地方读书。

He likes to go to the movie.

他喜欢去看电影。

She wants to help Mary.


她想要帮助玛丽。

She pretended not to go.

她假装不去。

He pretended to be a good man.

他假装是好人。

They agreed to have a meeting the next week.

他们同意下星期开会。

They just don’t stop to think.

他们就是不停下来想一想。

They stopped to have a rest.

他们停下来休息。（停下去做）

I have stopped smoking for half a year.

我已经半年不抽烟了。（停止做）

She remembered to surf the internet to get information.

她记得上网查信息。（记得要做）

I rememdered bring my homework.

我记得带作业了。（记得做过）

We happened to meet at the station.

我们碰巧在火车站相遇。

He happened to a teacher at the school.

他碰巧是学校老师。

2. 系表结构+动词不定式

glad，sorry，happy，sad，surprised，troubled等与情绪有关的形容词后常用动词不定式。

I am glad to see him.

我很高兴看到他。

Sue was troubled to see trash everywhere.

苏看到到处是垃圾很苦恼。

Sara was excited to see the rock band.

莎拉看到摇滚乐团很兴奋。

be likely to ... “…可能…”

He is likely to arrive at any time.

他可能随时会到。

His health is likely to get worse.

他的健康可能会恶化。


三. 动词不定式做宾语补足语

结构︰主语＋谓语＋宾语＋动词不定式

多数动词，常用的有 want，get，compel，expect，ask，would like，advise，urge，wish，tell，allow，permit，trouble，help，teach 等。

I told him not to give up.

我叫他不要放弃。

The teacher urged his students to prepare for the exam.

老师劝他的学生准备考试。

They forced me to do things against my will.

他们强迫我做违背我心意的事。

Do you want me to go there instead of you?

要不要我代你到那儿去？

I got him to do it.

我叫他做这事。

Their help enabled me to finish the work with ease.

他们帮助我，使我能够顺利地完成工作。

The father allowed (=permitted) his son to travel abroad alone.

父亲答应让他的儿子单独出国旅行。

We troubled him to turn on the light.

我们麻烦他打开电灯。

We needed someone to fix the tape recorder.

我们需要有人来修理录音机。

注意：动词不定式做make,have,let，hear,see，feel等动词宾语的补足语，要省略“to”

make/have sb. do sth.

I made him do it.

我叫他做这事。

I let him do it.

我让他做这事。

They had/made the girl clean the floor.

他们叫这个女孩打扫地板。

My father will probably have Tom paint the house green.

我爸爸很可能叫汤姆把房子漆成绿色。

He had me help him with his homework.

他叫我帮忙他做家庭作业。

Did you notice anyone come in?

你注意到有人进来过吗？

As far as I remember, I have never seen him smile.

在我记忆中，我从未见他笑过。

I felt my heart beat violently.

我感觉到自己的心跳得很厉害。

She liked to listen to children talk.

她喜欢听孩子们谈话。


四. 动词不定式做目的状语

To make sure that he was at home, I called him up in advance.

为了确定他在家，我事先打电话给他。

He came to China to learn Chinese twenty years ago.

他在20年前到中国学中文。

in order/so as + 动词不定式

He must work very hard in order to support his large family.

他必须拼命工作以养活他的大家庭。

Listen carefully so as to follow the teacher.

要仔细听才能听懂老师讲的课。

You must watch your step so as not to fall down.

你必须留心脚下才不会跌下去。

be used + 动词不定式

The book is used to teach us how to write.

这本书教我们如何写作。

The knife can be used to cut meat.

刀能用来切肉。

The book is used as a reference book.

这本书被用来做参考书。