It is uncertain side effects these weight-loss drugs will bring about, although hundreds of thousands of patients have taken it.
A. that
B. whether
C. how
D. what
网友回答
A. that
B. whether
C. how
(答案→)D. what
解析：
这句话考查的是主语从句，it是形式主语，因为是uncertain，所以主语是不确定的事，side effects缺少修饰，填what。句意是：虽然几十万患者采取了这些减肥药但是不确定它会产生什么副作用。选D。