一、不定式构成与形式
不定式由不定式符号“to”+动词原形构成(有时不带to),其否定形式是“ not to do”。不定式前面可以加某些疑问代词,如what、who、which,或疑问副词,如when、where、how、why等,构成特殊的不定式短语,如what to do next, how to get there等。不定式的逻辑主语有时用“ for十名词或代词宾格”构成。
不定式的形式有:
主动形式 被动形式
一般式 to do to be done
完成式 to have done to have been done
进行式 to be doing
完成进行式 to have been doing
二、不定式的用法
不定式不能单独作谓语,没有人称和数的变化,具有名词、形容词和副词的特征,而且还保留着动词的特征,因而可以有状语修饰,如果是及物动词,还可以带宾语,从而构成不定式短语。不定式或不定式短语在句中可以作主语、表语、宾语、定语、状语、主语补足语和宾语补足语。
1. 作主语.不定式短语作主语时,往往放在谓语之后,用it作形式主语。例如:
To see is to believe.
It is right to give up smoking.
2. 作宾语.不定式短语作宾语时,如果还带有宾语补足语。往往把不定式宾语放在宾语补足语之后,而用it作形式宾语。例如:
He wanted to go.
I find it interesting to study work with him.
3. 作宾语补足语.例如:
He asked me to do the work with him.
注意:在 feel,hear,listen to,look at,notice, observe,see,watch,have,let,make等词后的补足语中,不定式不带to.但是这些句子如果变成被动结构时,就必须带 to.例如
I often hear him sing the song.
He is often heard to sing the song.
注意:不定式动词在介词 but,except,besides后面时,如果这些介词之前有行为动词 do的各种形式,那么,这些介词后的不定式不带to,否则要带to。如:
She could do nothing but cry.
What do you like to do besides swim?
I have no choice but to go.
4. 作定语.例如:
I have some books for you to read.
注①作定语的不定式如果是不及物动词,或者不定式所修饰的名词或代词是不定式动作的地点、工具等,不定式后面须有相应的介词。例如:
He is looking for a room to live in.
There is nothing to worry about.
Please give me a knife to cut with.
但是,不定式所修饰的名词如果是time,place或way,不定式后面的介词习惯上要省去。例如:
He had no money and no place to live.
注②当作定语的不定式所修饰的名词或代词是不定式动作的承受者时,不定式既可以用主动语态,也可用被动语态,但其含义有所不同。试比较:
A) Have you anything to send?
你有什么东西要寄吗?
(不走式 to send的动作执行者是 you)
B) Have you anything to be sent?
你有什么要(我或别人)寄的东西吗?(不定式 to be sent的动作执行者是已被省略的me或someone else)