问题
选择题
Generally speaking_______acording to the
instructions，the drug has no side effect.
A．when taking
B．when taken
C．when to take
D．when to be taken
答案
答案：B
B 完整的说法应是when the drug is taken according to the directions，…。由于主句的主语和从句的主语相同，且从句中的谓语动词含有be的某种形式，因此可以省略从句的主语the drug和is。