【题目】It is uncertain ________ side effect the medicine will bring about, although about two thousand patients have taken it.
A. that B. what C. how D. whether
在线课程【答案】B
【解析】还原主语从句中的主干是the medicine will bring about ______ side effect。故选择what，形容词“什么样的”，起修饰作用。句意：尽管大约有两千名病人服用过这种药物，但是，它会带来什么样的副作用还不确定。