1 is staying

2 have known

3 How long have you been doing......

4 will go

5 Are the students at the library now?

6 didn't hear

7 I'm not

8 Is it snowing at the moment?

9 Does it often snow in November?

10 snows

11 Did it snow yesterday?

12 Will it snow tomorrow?

13 have been

14 starts

15 What are you doing this weekend?

16 doesn't live

17 haven't heard