— Have you called Mr. Johnson’s office? — Yes, he _____ back before tomorrow. So he can attend our meeting on time.
3. —How long are you staying there? — _____depends.
4. I hate _______ when young people speak to the elderly in a rude way.
5.Is ____ necessary to complete the design before National Day?
6.I don’t think ____ possible to master a foreign language without much memory work.
7.Does ______ matter if he can’t finish the job on time?