I often have conversations with John over telephone, while I keep in touch with Tom by letter.
A. /;the
B. /;a
C. the; /
D. the; a
网友回答
A. /;the
B. /;a
(答案→)C. the; /
D. the; a
解析：句意：我经常通过电话和约翰交谈，然而，我和汤姆用书信保持联系。前一个空over the telephone 表示“通过电话”；by letter 表示“通过写信”，by 表示方式后直接接一个名词。选C。