考点2、动词不定式:动词不定式没有人称和数的变化,在句子中不能做谓语。动词不定式具有名词、形容词和副词的特征,在句子中可以作主语、宾语、表语、定语和状语,它还具有动词的特点,可以有自己的宾语和状语。它的形式是to+动词原形,否定式为not to+动词原形。

(1)作主语:动词不定式作主语时,常用it作形式主语(it无词义),而将动词不定式放在后面,其形式为:It+be+形容词+(for sb.)+ 动词不定式

To learn a foreign language is important now.

→It is important to learn a foreign language.

It’s necessary for the students to do eye exercises twice a day.

It’s too heavy for the boy to carry the box. .

It takes him a quarter to cut the hair .

(2)作宾语和宾语补足语

①动词不定式一般不作介词宾语,常作及物动词的宾语,这些动词有want,begin ,start , like ,forget ,ask ,learn, decide , wish等

The boy wants to go to school.

He began to learn French three years ago .

②动词不定式在句中作宾语补足语用得很广泛,如:

He asked me to help him.

Tell him not to be late .

My parents tell me to study English hard .

I would like you to meet my English teacher .

 

③动词不定式在感官动词see,watch,hear,feel和使役动词let, make,have等词后作宾语补足语时,常省去不定式符号to 。另外在had better后也不带to ,help后可带可不带to .

I hear him sing every night .

Let’s go to school together .

Her mother makes her do her homework every evening .

You’d better stay at home .

I often help my mother (to) do some washing .

④疑问词+不定式作宾语,如:

He didn’t know where he should go .

→He didn’t know where to go .

I don’t know what I should do .

→I don’t know what to do .

We haven’t decided when we’ll leave here .

→We haven’t decided when to leave here .

(3)作表语,在系动词之后作表语

Her work is to look after the babies.

(4)作定语,动词不定式作定语,需放在被修饰的名词之后。

   I have quite a lot of homework to do .

(5)作状语,表示目的、原因、结果

   He came here to see his father .

   I’m sorry to hear that .

考点3、被动语态的用法

1).当我们不知道或没有必要说明动作的执行者是谁时.

Those books are written for children.

This jacket is made of cotton.

2).动作的承受者是谈话的中心,并用介词by引导动作的执行者。

Food is needed by us all .

The room is cleaned by me every day .

The book was translated into English by me .

This song was written by a friend of mine .

The thief was caught by a policeman yesterday evening .

The tree was blown down by the strong wind .

3).一些相当于及物动词的短语动词也可用于被动结构中,因此短语动词是一个不可分割的词组,不可丢掉后面的介词或副词。

The child is taken good care of by his grandparents .

Why can’t the word be looked up in this dictionary?

The lights must be turned off .

A short play will be put on at the party .

4).带双宾语(即直接宾语和间接宾语)的主动语态变为被动语态时,可将其中的一个宾语变为被动句的主语,另一个不变。一般把间接宾语变为被动语态的主语显得自然些,把直接宾语留作被动句的宾语。如果把直接宾语变为被动句的主语,则要在间接宾语前加介词(一般是for或to)

He gave me a book. →I was given a book (by him )

                   →A book was given to me (by him).

5).主动句中动词make , let ,have ,see ,hear , feel 等后接不定式作宾语补足语时,动词不定式都需去掉to,即后接不带的动词不定式。但变为被动语态时,后面的不定式须加上to .

I often hear her sing .→She is often heard to sing.

His parents made him clean his teeth after every meal.

→He was made to clean his teeth after every meal by his parents.

6).疑问词作主语的句子变为被动语态。

Who spoke English in the next room a moment ago ?

→By whom was English spoken in the next room a moment ago ?

Or: Who was English spoken by in the next room a moment ago?

7)有些动词的主动语态表被动含义。

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