问题
选择题
They are still very cautious about ______ side effect the new medicine will bring about, although the experts have tried it on about 2,000 patients.
A．which
B．that
C．where
D．what
答案
答案：D
题目分析：句意：他们对于这种新药会产生什么样的副作用还是很谨慎，虽然专家在2000个病人身上已经实验过了。这里about后面接的是宾语从句，宾语从句中side effects前面缺少定语，用what连接宾语从句，所以选D。