1. 给下列问句选择相应的答语。

A. Yes, it is. B. No, it isn't. The library is on the first floor. C. It's on the second floor. D. No, it isn't. The teachers' office is next to the library.

1. （1） Is this the teachers' office?
3. （2） Where is the library?
5. （3） Is the library on the second floor?
7. （4） Is Classroom 2 next to Classroom 3?