非谓语动词是指由动词变化而成，仍具有动词的性质与意义，但不能作为动词使用的词。通常有三种形式构成：

1. 由“to+动词原形”而成的不定式;

2. 由“动词原形+ing”而成的现在分词或动名词;

3. 由“动词原形+ed”而成的(包括动词的不规则变化)过去分词。

动词不定式的主要用法

1.To finish the work on time is not easy.(作主语)

(要准时完成这项任务并不容易。)

注意：动词不定式作主语时，也可以用形式主语“it”，

即It’s not easy to finish the work on time.

His wish was to become a teacher.(作表语)

(他的愿望是成为一名教师。)

There is nothing to worry about.(作定语)

(没有什么可以担心的。)

He ran to catch the bus. (作状语)

(他跑着去赶车。)

I want to see the new film.(作宾语)

(我想要去看这部新电影。)

He asked me to open the door.(作宾语补足语)

(他要我把门打开。)

注意：①动词不定式在作let,make,see,hear,feel,watch等使役、感观动词的宾语补足语时，不定式不带“to”

例：We often hear her sing in the next room.(我们经常听到她在隔壁房间唱歌。)

但上述动词用于被动语态的句子中，动词不定式变成主语补足语，这时必须带“to”。

例：He was heard to sing in the next room every morning.(明天早晨他总是被听到在隔壁房间唱歌。)

②动词不定式作宾语时，也可用形式宾语“it”。

例：They found it impossible to get everything ready in time.(他们发现及时准备好一切是不可能的。)

2.动词不定式也可以和疑问词who,what,which,whether,when,how,where等连用，构成不定式短语。

How to get the tickets is a question. (作主语)

(如何获得票子是个问题。)

I wonder which to choose. (作宾语)

(我不知选哪一个。)

The question is who to send the letter. (作表语)

(问题是谁去送信。)

1. for + 名词(代词)+动词不定式的复合结构

It is important for us to learn English. (作主语)

(对我们来说学英语是重要的。)

It is for you to decide. (作表语)

例：While talking with her teacher, she felt nervous.(当与老师讲话时，她感到紧张。);

On hearing the good news, she jumped up with joy.(她一听到这好消息就高兴地跳起来。)

4.当分词作状语时，分词的逻辑主语必须与句子的主语一致。

Seeing the house on fire, he immediately ran to the phone-box.

=When he saw the house on fire, he immediately ran to the phone-box.

(当他看到房子着火，他马上跑到电话亭去。)

Given more time, we could do it better.

=If we were given more time, we could do it better.

(如果我们被给更多的时间，会做得更好。)

5.有一类动词如interest,excite,surprise,please,disappoint,satisfy,tire等，它们的现在分词往往用来表示事物的性质;而它们的过去分词则用来表示人的感受。

I am very interested in the interesting story.

(我对这则有趣的故事很感兴趣。)

We are all tired of such a tiring question.

(我们都对如此一个乏味的问题感到厌倦。)

6.现在分词的被动式being done与过去分词的区别。

现在分词的被动式being done表示正在进行的被动动作，而过去分词则强调已经完成的动作或持续的被动状态。

The problem being discussed now is very important.

(正在讨论的问题很重要。)

The problem discussed yesterday was very important.

(昨天讨论过的问题很重要。)

I saw many cars being repaired.

(我看到许多车正在被修理。)

I found the window broken.

(我发现窗被打碎了。)

Being cooked, the chicken gave out a wonderful smell.

(在被煮的时候，鸡散发出极好的味道。)

Led by the party, we have won great achievements.

(在党的领导下，我们取得了巨大的成果。)(由你来决定。)

I don’t think it good for you to leave now.(作宾语)

(我认为你现在离开并不好。)

I have bought the books for you to read.(作定语)

(我已注意：only+分词与only+不定式的区别

“only+现在分词”的意思是结果只是;

“only+不定式”意思是想不到、反而并没有料到的结果：

He lifted a rock only to drop on his own foot.

(他搬起石头，想不到砸了自己的脚。)

He died, only leaving debts.

(他死了，只留下一身债。)

③不定式与分词作宾补时的区别：

不定式作宾补表示动作已经完成，强调动作发生过的这一事实，强调由此行动而产生的结果;而现在分词作宾补强调动作的过程即动作正在进行。

I found him coming into the building.

=I saw that he was coming into the building.

(我看到他正在走进大楼。)

I found him come into the building.

=He came into the building, and I saw that.

(我看到他走进大楼。)

注意：如在句子中出现often、seldom、usually等频度副词，表示动作的经常性，而不是动作正在进行，所以通常用动词不定式。