问题
选择题
It’s uncertain _______ side effect the medicine will bring about , although about two thousand patients have taken it ．
A．that
B．what
C．how
D．whether
答案
答案：B
考查宾语从句，it 做形式宾语，真正的宾语是后面的从句，而从句中bring about后缺少宾语，故用what,what又做定语修饰side effect，所以选B。