Question

It is uncertain      side effect the medicine will bring about , though about one thousand patients have taken it.

A．that

B．whether

C．what

D．how

Answer 1

C

解析试题分析：句意：尽管大约1000名病人使用了这种药，但它会带来什么样的副作用还不清楚。此处what修饰名词side effect。故选C。
考点：考查名词性从句的连接词。