it 在英语中可以做形式主语，可以代替那些成分？

Question

如题所述

Answer 1

it的用法总结：
1. 可以做代词，指代无生命的东西或者不辨性别的人。
如： I bought a book yesterday, and I like it very much.
whose baby is it?
who are knocking at the door? it's me.
2. it做无人称代词，指代时间，距离，天气等。
如：it 's cold today. it's nine o'clock. it's a long way there .
3. it做代词，在句子中做形式主语和形式宾语。
如： it took me 3hours to finish the work.
I don't think it a good idea to stay here just waiting.

Answer 2

it可以代替不定式和动名词