7.14 不定式的時態(tài)和語態(tài)
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時態(tài)\語態(tài)    主動     被動
一般式      to do      to be done
進行式      to be doing  
完成式      to have done   to have been done
完成進行式    to have been doing  

1) 現(xiàn)在時:一般現(xiàn)在時表示的動詞,有時與謂語動詞表示的動作同時發(fā)生,有時發(fā)生在謂語動詞的動作之后。
  He seems to know this.
  I hope to see you again. = I hope that I'll see you again. 我希望再見到你。

2) 完成時:表示的動作發(fā)生在謂語動詞表示的動作之前。
 I'm sorry to have given you so much trouble.
 He seems to have caught a cold.

3) 進行時: 表示動作正在進行,與謂語動詞表示的動作同時發(fā)生。
 He seems to be eating something.

4) 完成進行時:
 She is known to have been wreaking on the problem for many years.