--________ the population of Sichuan?--90 million people.
--- Listen! David is talking happily with his mother in the next room.--- It ______ be his mother. She has gone to Yunnan to be a volunteer doctor.
— Must I finish my homework now?— No, you ________. You can go home now.
-- Must I return the book this week?-- No, you ______. You can _____ it for 20 days.
I like this room. You ______ see the mountains from the window.
I'm very glad I have my own room in my house. I ______ do what I want in it.