—______do you write to your parents? -- Twice a month.
Pollution is a serious problem. Scientists have to _____ some good ways to save it.A. come up with B. come on C. come out
You shouldn’t ________ your hope. Everything will be better.A. give up B. fix up C. cheer up
_____Daming’s help , they solved the problems successfully .A.As for B.Thanks for C.Thanks to
The driver saw an old man _______ on the side of the road .A.lie B.lay C.lying
Bob used to __in the countryside . But now he is used to ____in the big city .A.live ; live B.live; living C. living ; living