he went abroad in 2006.______we have kept in touch with each other by writing e-mail.
问题描述：
he went abroad in 2006.______we have kept in touch with each other by writing e-mail.
A.when B.since C.after that D .since then
觉得都挺通的
答
正解是D,
这个主要看后面句子是have kept 是完成时,那就得用since then
after that 就该用过去时态.