同学你好，该知识点来自沪江网校《新概念英语第一册【随到随学班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好！

it常见的几大用法如下：

一、指无生命、动物、植物和在性别不计或不详时指人和婴儿。There is a person knocking at the door. Who can it be?
二、指心目中的人或上文中提到的人或事物，这那它    He is fifty-two, but doesn't look it.
Jim is ill. Have you heard of it?
三、可以代替指示代词this和that
What's this/that？  ------It's a book。
四、作无人称代词的主语，表时间、天气、距离、温度、环境和情况。It was noisy when I got to the room.