—Do you know the artist _______ the judges gave a prize?

—Yes. He is the teacher _______ I have been taught painting for two years. [ ]

A. to whom, by whom

B. for whom, by whom

C. to whom, form whom

D. for whom, on whom

在注射剂生产过程中使用活性炭的目的是（）.

A.脱色

B.助滤

C.吸附热原

D.提高澄明度

E.增加药物的稳定性