the unwritten rule goes, study is good, but health es first.
A. Which
B. That
C. As
D. What
网友回答
A. Which
B. That
(答案→)C. As
D. What
解析:考查非限制性定语从句:as引导非限制性定语从句,意思是“正如”,as在定语从句中做主宾表,这句话里面的goes是及物动词,表示“说”,as指代主句的内容,which也可以引导非限制性定语从句,但是意思是“这个,那个”,也不能放在句首,that不能定语非限制性定语从句,what不能引导定语从句,句意:这个不成文的规定说:学习好但健康是第一位的。选C。