问题补充：
E-mail, as well as telephones, an important part in daily communication.
A. is playing
B. have played
C. are playing
D. play
答案：
(答案→)A. is playing
B. have played
C. are playing
D. play
解析：考察主谓一致。本题的主语是E-mail, as well as telephones；谓语动词要和前面的E-mail保持一致，故使用单数形式。句意：电子邮件和电话在日常交流中正在起着一个很重要的作用。选项中只有A项是单数形式。故A正确。
