--How do you improve your listening skill Mary? ----I often do it tapes and English r

问题补充：

----How do you improve your listening skill, Mary?

----I often do it tapes and English radios.

A. by hearing

B. in listening to

C. by listening to

D. for listening

答案：

A. by hearing

B. in listening to

(答案→)C. by listening to

D. for listening

解析：句意：Mary,你是怎么提高听力技能的？我经常通过听磁带和英语电台来提高。By doing sth.通过做某事，by表示方式，故选C。