问题 选择题

Fighting an artificial greenhouse effect seems to be the greatest of environmental challenges, ________?

A.isn't it

B.does it

C.doesn't it

D.is it

答案

答案:C

C 考察反义疑问句。当反义疑问句的陈述部分是肯定形式的时候,疑问部分使用否定形式,排除BD,根据陈述部分的seems可知doesn’t it符合题意。故C正确。

单项选择题
单项选择题