问题补充：
Some people get in touch with each other by mobile phones others keep contact with each other by e-mail.
A. while B. before C .when C. since
答案：
解析：可联系答.案.网客服索取。
如果觉得《Some people get in touch with each other by mobile phones others keep contact with each ot》对你有帮助，请点赞、收藏，并留下你的观点哦！
