语法入门14.doc

第十四课.动词不定式 在英语句子中，动词有两类，一类是谓语动词，另一类是非谓语动词。如“I work”一句中，work 作谓语动词，如果把句子改成“I want to work”，句中的谓语动词则变成了want。而to work就是非谓语动词。非谓语动词有三种，即动词不定式，分词（现在分词和过去分词）和动名词。 动词不定式的定义 不定式是动词的一种非限定形式。不定式没有人称和数的变化，不受主语人称和谓语动词的时态变化干扰。在句中不能单独做谓语，但仍然保留动词的特点，即可以有自己的宾语和状语。不定式同它的宾语或者状语构成不定式短语。 动词不定式的基本形式 不定式的基本形式是“to+动词原形”有时可以不带to，to仅是符号，本身没有意思。 动词不定式的时态和语态 不定式有进行体和完成体，也有被动态。不定式有以下时态和语态的变化。 主动形式 被动形式 一般式 to do to be +表语 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 动词不定式的句法作用 由于动词不定式具有名词，形容词和副词的特征，所以它在句中可以作主语，表语，宾语，定语，状语，宾补。作主语 To help poor people is our duty. To master English is easy. To swim in the river is funny. To learn English grammar is necessary. To get there by bike took me two hours. To sing English songs makes me happy. 在多数情况下,特别是在口语中,常常用引词it来代替不定式作主语,而把不定式移到句子后面,这样使句子显得较平稳. It is our duty to help poor people. It is easy to master English. It is funny to swim in the river. It is necessary to learn English grammar. It took me two hours to get there by bike. It makes me happy to sing English songs. 如果要说明不定式表示的动作是谁做的,可以在不定式前面加for引起的短语,既“for +名词（代词的宾格）+不定式”。在这一结构中的for本身没有意义。名词（代词的宾格）形式上是for的宾语，但意义上是不定式可以说是不定式的主语，既不定式的逻辑主语，以区别于语法上的主语。 It is good for us to eat an apple a day. It is not hard for us to finish the work before noon. It is easy for you to win the game. 某些表示人的品行的形容词（kind good nice wrong careless wise foolish polite clever right unwise stupid thoughtfull rude silly impolite等）作表语的时候，不定式前常可用of引起的短语，既“Be+形容词+of +名词（代词的宾格）+不定式”。 It is kind of you to repair my bike. It was stupid of her to make such a mistake. It is unwise of him to go there alone 作表语 Her wish is to become a pop singer. Our plan is to finish the work in two days. My wish is to be a boss. My plan is to buy a villa next year. 作宾语 I want to buy a house next year. He learns to repair buses. I started to teach her English last year. I try to help him. I chose to be a teacher. She decided to sell her computer. I try to be happy every day. 能直接加不定式作