Question

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

Answer 1

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。