Ⅰ.写出下列句中it的用法
1．I have lost my book; where is it?
it指代前句中提到的书。
2．What a beautiful baby — is it a boy?
it指代前句中提到的婴儿。
3．It's a beautiful day here and I am sitting under the big tree at the end of the garden.
it指代天气。
4．It's my birthday in two weeks' time and I'll be 82 years old!
it指代时间。
