In time of serious accidents，______we know some basic things about first aid, we can save lives.

A. of whom B. whom C. of whose D. whose

A.didn’t work B.couldn’t work C.can’t work D.doesn’t work

I’d like to B. I like it C. I don’t D. I will

off B. away C. from D. up

A. which B. who C. what D. where

A. keep up B. keep back C. keep off D. keep away

A. Dressed; noticed B. Dressing; noticing C. Dressing; noticed D. Dressed; noticing

A.good B.better C.best D.the best

A.people smoking B.people smoke

C.to smoke D.smoking

A.Have … shown B.Do … show

C.Had … shown D.Did … show