什么时候用动词不定式

含有带to的动词不定式句型：
1. It’s time to do sth.
2. It takes sb. some time to do sth.
3. tell/ask/want/encourage/invite/ sb. to do sth.
4. Would you like to do sth.?
5. It’s good/bad to do sth.
6. It’s good/bad for sb.to do sth.
7. be+adj.+enough to do sth.
8. sb. is ready to do sth.
9. It’s+adj.+ for sb. to do sth.
10. It’s+adj.+ of sb. to do sth.
11. would like/love /decide/want/wish/to do sth.
12. would like/love sb. to do sth.
13. Prefer to do sth. rather than do sth.
I prefer to stay at home rather than go out.
14. what/how/ when/where/whether to do sth
15. can’t wait to do
16. too … to do …
17. be afraid /ready/able/sure to do
18. seem to do

非 谓 语 动 词 的 用 法

非谓语动词：在句子不作谓语使用的动词，其形式有不定式、现在分词、动名词和过去分词四种（通常我们把现在分词和动名词统称为-ing分词）。

非谓语动词短语：非谓语动词仍保留动词的性质，可以有自己的宾语、表语或状语，我们将非谓语动词和其宾语、表语或状语一起称作非谓语动词短语。

非谓语动词的判定方法：考虑句中谓语动词以及其它词语同非谓语动词的关系和对非谓语动词形式的限制，以便选用正确的非谓语动词形式。

非谓语动词判定的基本步骤：①是否应用-ing分词 ② 是否应用不带to的不定式 ③ -ing分词还是不定式④-ing分词还是过去分词 ⑤ 不定式的用法

一、是否应用-ing分词：下列情况必须用-ing分词

1、在下列动词（短语）之后作宾语或宾补时；

Consider , dislike , enjoy , feel like , finish , imagine , mention , give up , mind , put off , can’t help , can’t stand , suggest , understand , be busy , have fun , have difficulty , have trouble, keep , spend , waste , have a hard time , find , look forward to , be use to(习惯于) ，prefer ( doing ) to ( doing ) ，take turns等。

e.g When she heard the news, she couldn’t help crying.

I found a boy playing in the corner.

2、在介词之后作宾语时；

e.g Lucy is good at swimming.

3、作句子主语位于句首时；

e.g Exercising every day is good for your health.

4. 位于限定词后作名词使用时；

e.g This is the beginning of the garden tour.

5、在“go + -ing形式（运动名称）”和“ do some + -ing形式”这类固定短语中。

e.g We will go fishing if it doesn’t rain tomorrow.

She did some shopping last Sunday.

6. –ing分词前逻辑主语的使用：有时我们需要在-ing分词前加上其动作的发出者（逻辑主语），其动作的发出者用名词所有格或形容词性物主代词表示。

e.g Would you mind my smoking here?

二、是否应用不带to的不定式： 下列情况必须使用不带to的不定式

1、位于情态动词后同情态动词一起作谓语时；

e.g You should see a dentist if you have got a toothache.

2、位于would rather , had better , why (not)之后的不定式；

e.g You had better stay here until the police come.

Why not go to the movie with us?

3、位于感官动词和使役动词后作宾补的不定式（注：help之后作宾补的不定式可以带to也可不带to）；

e.g I often hear her sing English songs in the next room.

The boss made them work over 12 hours a day.

She often helps her mother (to) do the housework.

4、两个不定式由and , or , except , but 或 than连接在一起时，第二个不定式常常不带to。

e.g I’d like to lie down and have a good rest.

三、-ing分词还是不定式：

1、动词like之后，使用不定式主要说明一次性的动作；使用-ing分词主要说明存在的状况。

e.g I like playing soccer, but I don’t like to play it this afternoon.

2、begin和start之后，-ing分词和不定式都可使用，但如果begin/start自身为-ing分词时，之后通常用不定式。

e.g He began to do/doing his homework after dinner.

I’m starting to cook dinner very soon.

3、stop、remember、forget和go on之后的非谓语动词形式的判定，主要应考虑非谓语动词的动作在谓语动词动作前是否已发生：如动作发生在谓语动词的动作前，用-ing形式；如动作发生在谓语动词的动作后，用不定式。

e.g The teacher is coming, please stop talking.

On her way home, she stopped to buy some food for supper.

Don’t forget to turn off the light when you leave.

He did his homework again. He forgot doing it yesterday.

4、need之后的非谓语动词形式的判定，主要考虑句子的主语同非谓语动词的关系：如句子的主语为非谓语动词的逻辑主语，用不定式；如句子的主语为非谓语动词的逻辑宾语，用-ing形式。

e.g We need to water the flowers this afternoon.

The flowers need watering this afternoon.

5. 感官动词后的非谓语动词形式的判定，主要应考虑是说明整个动作（不带to的不定式），还是说明动作的一部分（-ing形式）。主要有下面几种情况：

（1）句子中有表频率的词时，用不带to的不定式；

e.g I often hear Lucy sing songs in the classroom.

（2）look at以及see和hear的过去式后，一般用-ing形式；

e.g I saw the children playing soccer on the playground.

（3）watch之后，一般用不带to的不定式。

e.g He sat there and watched them play basketball.

四、-ing分词还是过去分词：

1. 表伴随的插入语中的非谓语动词形式的判定，主要应考虑句子的主语同非谓语动词的关系：如句子的主语为非谓语动词的逻辑主语，用-ing形式；如句子的主语为非谓语动词的逻辑宾语，用过去分词。

e.g When asked where she was from, she couldn’t help crying.

Taking some papers in his hand, Mr. Smith hurried into the classroom.

2. call和name位于名词后，其后带上人名、书名等词语时，用过去分词。

e.g Do you know the boy named Jack Black?

Yesterday we saw an action movie called Heroes.

3. there be句中位于名词后的非谓语动词，如名词相当于动作发出者（主动式），非谓语动词用-ing分词，如名词为动作承受者（被动式），非谓语动词用过去分词。

e.g Listen! There is someone crying for help.

There is little time left. Let’s hurry up.

五、不定式的用法（非上述四种情况时，非谓语动词一般都使用带to的不定式）：

1．不定式的否定形式：在不定式的小品词to前加否定词not。

e.g The policeman told the boys not to play soccer in the street.

2. 先行词it的使用：当不定式做句子的主语时或做句子的宾语其后带有宾补时，为保持句子结构的平衡，通常将不定式放在句子末尾，而在原主语或宾语的位置上加上先行词it。

e.g It is necessary for us to read English every morning.

I found it necessary for us students to read English every morning.

3. “wh-词+不定式”的用法：wh-词（特殊疑问词）同不定式连用相当于一个wh-词所引导的一个宾语从句，使用时应注意以下原则：

①如wh-词为疑问代词（what、which、who、whom或whose）时，不定式动词应为及物动词，但不带宾语（wh-词相当于不定式动词的宾语），如不定式动词为不及物动词，应带上适当的介词。

e.g There were too many things on sale. I didn’t know what to buy.

I really don’t know what to talk about at the meeting.

②如wh-词为疑问副词（how、when、where等）时，不定式短语中不能再出现表示相同关系的词语；另：如不定式动词为及物动词时，其后必须带上宾语。

e.g I don’t know how to do it.

③如wh-词为连词whether时，不定式短语中应有表示选择的部分，否则不定式短语应用or not结尾。

e.g He wants to know whether to go to a movie or stay at home.

I wondered whether to buy a computer or not.

一般情况下，我们应记住三个短语：what to do、how to do it和which to choose。

4. 不定式的逻辑主语：不定式动词仍保留动词的特性，也有自己的主语（不定式动作的发出者），我们将不定式动作的发出者称为不定式的逻辑主语。

不定式的逻辑主语通常是句子的主语或间接宾语：

e.g He went to the town to buy some book yesterday.

He asked me to have dinner with him this afternoon.

有时不定式的逻辑主语不是句子的主语或宾语（不定式作主语时），我们应在不定式前使用介词短语for s.b/of s.b为其加上逻辑主语：

e.g It’s necessary for us students to study English well.

It’s very kind of you to help me so much.

注：逻辑主语前介词for和of的选用，应考虑其前形容词的作用。如其前形容词用来说明不定式，逻辑主语前的介词用for，如说明逻辑主语，介词用of。

5. 不定式的逻辑宾语：有时句子中不定式前的某个词语相当于不定式的宾语，我们将其称为不定式的逻辑宾语，此时不定式的动词应为及物动词或及物动词词组（动词为不及物动词时，应加上适当的介词），但不能再带宾语。

e.g 错：The question is too difficult for me to answer it.

对：The question is too difficult for me to answer.

错：The computer is too expensive for me to pay.

对：The computer is too expensive for me to pay for.

6. 不定式位于名词后作定语：不定式位于名词后作定语使用时应注意考虑名词同不定式的关系。

①名词相当于不定式的逻辑主语：

e.g He is the first Chinese pianist to win this prize.

②名词相当于不定式的逻辑宾语：此时不定式的动词应为及物动词或及物动词词组（动词为不及物动词时，应加上适当的介词），但不能再带宾语。

e.g Today we have much homework to do.

③名词相当于不定式的状语：此时不定式应以介词结尾（因为名词不能直接作状语，而应在其前加上适当的介词构成介词短语用来作状语，说明地点、方式等，所加的介词这时放在不定式后）。

e.g First we have to find a restaurant to eat dinner in.

He wants to find a partner to practice English with.