Olny __acccording to the directians can the medicine be quit

我怎么读来读去都觉得应该是B呢?在taken 前加上个being?是什么结构?
很显然不是独立主格,那么为什么要加being?原句好像没有强调现在进行的意味,而是表达一个常规的惯例,我认为只用被动语态就可以了.

C

答案为C。倒装句型强调“按要求服药”的重要性。“being taken”为分词代替从句。句子原始表达为：“Medicine can be quite effective only when it is taken according to the directions.”

Only __acccording to the directions can the medicine be quite effective.
A:taking
B:taken
C:being taken
D:having been taken

答案应该是C
这个句子是only短语放在句首的半倒装句，翻译成：只有……才能。本句翻...

c
Only being taken according to the directions can the medicine be quite effective.
只有按指示服用,药才有效.
主语medicine是被吃,所以用被动语态