三、非谓语动词 不定式(to + V)
动名词
分词-ing
分词-ed
(一)动词不定式(to+动词原形)
动词不定式的语法功能
可以做除谓语动词以外的任何句子成分。
1)作主语
不定式或不定式短语作主语时，谓语动词用第三人称单数。如：
To serve the people well is our duty.
动词不定式短语作主语时，往往放在谓语动词的后面，用引导词it作形式主语。上述句子也可改为：
It is our duty to serve the people well.
类似这样不定式做主语的句型有:
It is + n.+ to do
It takes sb.+ some time + to do
It is +adj.+ for sb.+ to do
It is + adj.+ of sb.+ to do
例如：
It is our duty to help them.
It will take you quite a long time to finish it.
It is easy for us to answer this question.
It is kind of you to help me.
注：
1)for sb.常用于表示事物的特征特点，表示客观形式的形容词，如easy, hard, difficult, interesting, impossible等：
2)of sb.的句型一般表示人物的性格，品德，表示主观感情或态度的形容词，如good, kind, nice, clever, foolish, right等。
2)作宾语
We hope to have more opportunities to talk with native speakers.
注意：
如果不定式作宾语而又跟有补语，这时，通常要用"it"作形式宾语，而将不定式放到补语后面去。
例如：
他们发现提前把一切都准备好是不可能的。
×They found to get everything ready in advance impossible.
宾语 宾补
×They found to get everything ready in advance is impossible.
√They found it impossible to get everything ready in
宾补 宾语
advance.
再看下面的两个例句：
I consider it my duty to point out their shortcomings.
Robert doesn't think it advisable for Mary to be on a diet.
三级出题方式：
I _____ to point out their shortcomings.
A.consider it my duty
B.consider it is my duty
3)作定语
This is the best way to solve the problem.
注意：
①用不定式作定语时，它与它所修饰的词有时是动宾关系，所以如果不定式是不及物动词，其后面应跟上必要的介词。
例如：
Mary needs a friend to play with.
There is nothing to worry about.
Because air pollution has been greatly reduced, this city is still _____ .
A.a good place to live
B.a good place for living in
C.a good place to be lived in
D.a good place to live in
答案：D
②不定式作定语，如果与他所修饰的词是动宾关系，则不定式后面不能再带宾语。
例如：
×Here is a letter for you to type it.
√Here is a letter for you to type.
×The smell tells the bees what kind of flowers to look for them.
√The smell tells the bees what kind of flowers to look for.
同时要注意：在这类结构中，常用不定式的主动式代替被动式。
4)作状语
In order to overcome difficulties, we must work hard.
注意：
①不定式能够修饰作表语或宾语补足语的形容词，在句中作状语，这时不定式不能再带宾语。
例如：
√The water is unfit to drink.
×The water is unfit to drink it.
√They found Mr.Jones' lecture hard to understand.
×They found Mr.Jones' lecture hard to understand it.
同时要注意：在这类结构中，常用不定式的主动式代替被动式。
②作状语的不定式的逻辑主语必须与句子主语一致。
例如：
×To save money, the bus was taken instead of plane.
√To save money, we took the bus instead of plane.
让我们看一道2005年11月份的三级试题：
To succeed in a scientific experiment,______.
A.one needs being patient person.
B.patience is to need.
C.one needs to be patient.
D.patience is what needed.
答案：C
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