______ is known to all, too much smoking will cause lung cancer.

______ is known to all, too much smoking will cause lung cancer.
A、That
B、It
C、As
D、What
【正确答案】：C
【题目解析】：as在此处做代词用，指代“too much smoking will cause lung cancer．”[译文]众所周知，过量吸烟将易得肺癌。