Generally speaking, _______ according to the directions, the drug has no side effect.
A. when taking B. when taken
C. when to take D. when to be taken
Generally speaking, _______ according to the directions, the drug has no side effect.
A. when taking B. when taken
C. when to take D. when to be taken
解析：选B。考查状语从句的省略。when taken是when the drug is taken的省略。