—If there are _________cars, there will be _________air pollution. —Yes. And the air will be cleaner.
There are _______ students in this school.
How long have you _______ the bike?
Once upon a time, an old man tried _______ the mountains.
---- Mum, may I go out and play basketball ? ---- Well, if you _______ your homework, you can.
Your _______ is really beautiful. Can you sing another song?