非谓语动词的一般式和完成式

非谓语动词的一般式表示的动作与谓语动词表示的动作同时发生或在其后发生，非谓语动词的完成式表示的动作发生在谓语动词表示的动作之前。

1.动词不定式

例1：A lot of young people are learning to drive cars. (同时发生)

例2：All of us expected to discover a new oil field. (非谓语动词动作发生在后)

例3：He is said to have studied English for three years. (非谓语动词动作发生在前)

注：动词不定式的完成式有时用在intended, expected, meant, were to, was to等过去式的动词后面，表示未实现的行为。例如：

1)I meant to have sent the book to you by mail. （我本想把这本书邮寄给你的。）

2)He was to have been the new ambassador, but he fell ill. (他原是要任新大使的，但是他病了。)

2.动名词

例1：I am thinking of getting a new dictionary. (非谓语动词动作发生在后)

例2：We enjoy watching colour TV. (与谓语动词动作同时)

例3：He forgot having promised to write things for us. （非谓语动词动作发生在前。）

3.分词

例1：Singing a song, he came into the room. （非谓语动词动作与谓语动词动作同时发生）

例2：Having written his composition, he went to have a heart to heart talk with Wang. (非谓语动词动作发生在前)