The question new measures should be taken to control the terrible air pollution is puzzles scientists a lot.
A. that; what
B. which; that
C. what; what
D. which; that
网友回答
A. that; what
B. which; that
(答案→)C. what; what
D. which; that
解析：考查同位语从句和表语从句。句意：应该采取什么样的新措施来控制空气污染的问题，是让科学家非常困惑的事情。根据句意可知，既然是question，就说明措施并不明确，应该是“什么样的new measures”，that引导同位语从句时，没有词义，不选A；is后的表语从句缺少主语，排除B、D；故选C。