Only when according to the directions strictly will the medicine work well.
A. taking
B. to take
C. taken
D. being taken
网友回答
A. taking
B. to take
(答案→)C. taken
D. being taken
解析：考查非谓语动词。这是一个倒装句。only +状语放在句首使用部分倒装，句中的主语the medicine与take之间是被动关系，应用过去分词。句意：只有当这种药严格地按照说明吃的时候，效果起得更好。所以选C。