Generally speaking according to the directions the medicine has no side effect.A. when

问题补充：

Generally speaking, according to the directions, the medicine has no side effect.

A. when taken

B. when taking

C. when to take

D. when to be taken

答案：

(答案→)A. when taken

B. when taking

C. when to take

D. when to be taken

解析：考查省略句。当状语从句的主语和主句主语一致的时候，且含有be动词的时候；可以把状语从句的主语和be动词一起省略。本题在when后面省略了the medicine is；句意：一般说来，当安装说明来服药的时候，药是没有副作用的。故A正确。