----_______ do you brush your teeth?
----- Twice a day.
A .How much B. How often C. How long
I _____ ask my father to give up smoking. It’s bad for his lungs.
A. must B. need C. shouldn’t
It’s cold outside, you’d better not _____ out.
A. to go B. go C. going
Why _______ climb mountains this weekend?
A. don’t B. didn’t C. not
There _______ a school sports meet next weekend.
A. is going to have B. is C. is going to be
As we know, water is very important _______ us.
A. of B. to C. on
