Question

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

Answer 1

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。