用特殊疑问词填空。

1. — ______ did he go? 

    — By plane.

2. — ______ did you live at the time? 

    — At No.3, Beijing Road.

3. — ______ is your telephone number? 

    —It's 3065431.

4. — ______ were you then? 

    —I was twenty-six.

5. — ______ car is yours?

    —The blue one.

6. — ______ is it from here to your house? 

    — About two miles.

7. — ______ was it yesterday?

    —It was Tuesday.

8. — ______ students are there in the classroom'?

简述给水系统的分类。