I often have conversation with John over phone, but keep in touch with Tom by writing le

I often have conversation with John over phone, but keep in touch with Tom by writing letters.
A. /; the
B. /; a
C. the; /
D. the; a

A. /; the B. /; a(答案→)C. the; /D. the; a解析：考查冠词。第一空为固定短语：通过电话over the phone，第二空：写信write letters，letters前不需要加冠词，所以选C。

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