You will fail your next exam ______ you start to work hard at your study now.
--________do you learn computer programming?--________asking my uncle for help.
There are three ________ and two ________ in the meeting room.
The number of the students in our class ________ forty-eight. A number of them ________ to school on foot.
A lot of trees ________ around here every year, and we can enjoy fresher air now.
_____ of the students in our class _____ girls.