it 除了指代事物外，还有多种特殊用法，是初中英语的重点。
要点讲解
- 指代天气、时间、距离、环境等：It is rainy today. 今天下雨；It's ten o'clock. 十点了。
- 作形式主语：It is important to learn English well. 学好英语很重要。（真正主语是 to learn English well）
- 作形式宾语：I find it easy to do the job. 我发现做这个工作很容易。
- 指代前面提到的人（尤其不明性别或婴儿）：Who is it? It's me. 是谁？是我。
- 用于强调句型：It is...that...：It was Tom who broke the window. 是汤姆打破了窗户。
- 固定句型：It takes sb. some time to do sth. 做某事花费某人多长时间；It's time to do sth. 该做某事了。
经典例句
- It takes me half an hour to walk to school.
我步行到学校要花半小时。 - It is kind of you to help me.
你能帮我真是太好了。 - It's time for class.
该上课了。
易错提醒
- It is + adj. + for sb. to do sth.（描述事物特征用 for）与 It is + adj. + of sb. to do sth.（描述人的品质用 of）要区分。