动词不定式用法123

南昌十九中  宋焘

    动词不定式由“to+动词原形”构成，具有名词、形容词和副词的句法功能，在句中可以作除了谓语以外的其他成分。

  1、动词不定式在句中的功能

  1）、做主语

  不定式做主语时谓语动词用第三人称单数，有时为了避免句子出现“头重脚轻”现象，常用it作形式主语，而把不定式放在句尾。

  To learn English well is not easy.

  It is not easy to learn English well.

  2）、作宾语

  不定式作宾语，跟在及物动词后面，这类动词有：want，wish，like，decide，help，start，begin，forget，try，hope等，有的动词要求不定式带上疑问词（who，when，how，where，which等）构成的短语作宾语。如：show，know，tell，teach，learn等。

  He decided to help her.

  I don't know how to tell you the news.

  有时不定式宾语后面还带有补足语等其他成分时，常用it作形式宾语，把不定式宾语放在宾语补足语之后。如：

  I found it difficult to find a new job in the city.

  3）、作表语

  My wish is to reach there on time.

  Our idea is to climb up the mountain from the north.

  4）、作宾语补足语

  宾语补足语放在宾语的后面，补充说明宾语在干什么。如：

  My brother asked me to clean the room with him.

  Would you like me to stay here with you?

  值得注意的是，某些动词后面带不定式作宾语补足语时要省掉标志to，这些动词常见的有：let，hear，make，see，feel，watch，notice等。如：

  The policeman saw a child play in the street.

  The boss（老板） made them work more than 12 hours a day.

  4）、作定语

  不定式作定语要放在被修饰语的后面。

  I have good news to tell you.

  She is the first to come to school.

  5）、作状语

  不定式作状语表示目的时可放在句首或句尾。

  To learn English well, you must study hard every day.

  He came here to ask for his book.

  当用作程度、结果状语时常与副词enough或too连用。

  He is old enough to go to school.

  He is too young to go to school.

  2、不定式的否定结构

  不定式的否定结构由“not+不定式”构成。

  Please tell your child not to play in the street.

  3、不定式的复合结构

  不定式的复合结构由“for\of + sb. +不定式”构成。用于当不定式动作的逻辑主语不是句子的主语时。

  It's impossible for us to finish that work in a day.

  The car is too expensive for me to buy.

  It's very kind of you to help me.

  此时，当句子的表语同时也是不定式逻辑主语的本质特征、特性等时，一般选择of结构。如：

  It's very nice of him to lend me his bike at that moment