不定式的特殊句型so as to

　　1) 表示目的;它的否定式是so as not to do。

　　Tom kept quiet about the accident so as not to lose his job.　湯姆對(duì)事故保持沉默是為了不丟掉他的工作。

　　Go in quietly so as not to wake the baby. 輕點(diǎn)進(jìn)去，別驚醒了嬰兒。

　　2) so kind as to ---勞駕

　　Would you be so kind as to tell me the time? 勞駕，現(xiàn)在幾點(diǎn)了。

　　不定式的特殊句型Why not

　　"Why not +動(dòng)詞原形"表達(dá)向某人提出建議，翻譯為："為什么不……?" "干嗎不……?"

　　例如：Why not take a holiday?　干嗎不去度假?

　　不定式的時(shí)態(tài)和語(yǔ)態(tài)

　　1) 現(xiàn)在時(shí)：一般現(xiàn)在時(shí)表示的動(dòng)詞，有時(shí)與謂語(yǔ)動(dòng)詞表示的動(dòng)作同時(shí)發(fā)生，有時(shí)發(fā)生在謂語(yǔ)動(dòng)詞的動(dòng)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(jiàn)到你。

　　2) 完成時(shí)：表示的動(dòng)作發(fā)生在謂語(yǔ)動(dòng)詞表示的動(dòng)作之前。

　　I'm sorry to have given you so much trouble.

　　He seems to have caught a cold.

　　3) 進(jìn)行時(shí)： 表示動(dòng)作正在進(jìn)行，與謂語(yǔ)動(dòng)詞表示的動(dòng)作同時(shí)發(fā)生。

　　He seems to be eating something.

　　4) 完成進(jìn)行時(shí)：

　　She is known to have been wreaking on the problem for many years.