问题
Only when___________ according to the directions can the medicine be quite effective.
A:taking
B:taken
C:being taken
D:having been taken;
B:taken
C:being taken
D:having been taken;
正确答案是：
同类题型
The hole is ____ to hold the roots of the plants.
What action should they _______ such a thing happening again
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ou seen Jane this week—No, but I ________ her call on my way to work thismorning