动词不定式
是由 to + 动词原形构成,在句中起名词,形容词和副词的作用,可以担任除谓语以外的其它任何成分.
1 动词不定式作主语：
To mast a language is not an easy thing.
掌握一门语言不是一件容易的事情.
To teach English is my favorite.
教英语是我的爱好.
It's my pleasure to help you.
动词不定式作主语时可以放在后面,而用 it 作形式主语放在原主语的位置上.
It's very kind of you to have given us much help.
你给了我们那么多的帮助真是太好了.
It's necessary to find the witness.
有必要找到目击者.
2 动词不定式作宾语：
某些及物动词可以用动词不定式作宾语,这些动词有decide,begin,help,begin,want,wish,like,forget,learn,ask.
What I wish is to learn English well.
我所希望的是把英语学好.
I like to help others if I can.
如果有可能的话,我喜欢帮助别人.
3 动词不定式作宾语补语 .
We expect you to be with us.
我们希望你和我们在一起.
Please ask him to come here quickly.
请叫他快过来.
4 动词不定式作表语 ：
What I should do is to finish the task soon.
我应该做的是赶快完成任务.
The most urgent thing is to find the boy immediately.
当务之急是马上去找孩子.
5 动词不定式作定语：
There are many ways to solve the problem.
有许多方法能解决这个问题.
I have something important to tell you.
我有重要的事情要告诉你.
6 不定式作状语：
We went to the hospital to see our teacher.
我们去医院看了我们的老师.
She is making a test to get a kind of useful
medicine from a Tibet flower.
她在做试验,从一种西藏花中提取某种有用的药物.
动词不定式的否定形式：
not + to + 动词原形
The teacher told us not to swim in that river.
老师告诉我们不要在那条河里游泳.
It's unfair not to tell us.
没告诉我们真是不公平.
