Question

Cheap coal ________ a lot of smoke．

1. A.
   gives up
2. B.
   gives in
3. C.
   gives away
4. D.
   gives off

Answer 1

D
give off的意思是send out smoke(vapour, etc)相当于“释放(出)烟、蒸汽”等；give up放弃；give away赠给，泄密；give in屈服，让步，其后带有宾语，要用介词to，故只有答案D符合题意。