It is kind of you to stay so =You are kind to say so.
18. It is necessary (for sb) to do sth
该句型与上一句统属一个句型。如果不定式的逻辑主语是由for 引出的,主句的形容词通常是表示重要性,紧迫性,频繁程度,难易,安全等情况的形容词。常见的形容词有:
Important,necessary,natural,easy,safe,common,,normal,hard,difficult,dangerous,unusual,grape, impossible, pleasant.等。
It is important for her to come to the party. =It is important that she (should) come to the party.
19. It looks (seems) as if …
该句型中it 无意义。As if 引导一个状语从句,常译为:“看起来好像……”如果与事实不相符合,则用虚拟语气。
It looks as if he is ill. (真的病了)
It looks as if he was ill. (事实上没有生病)
It seemed as if he was dying.
20. We think it important to learn a foreign language.