The major problem with E-mail is that it is (71) easy to use that people can become (72) with messages (73) they can possibly answer in a day. In addition, mail boxes require some management to (74) messages or archive those that might be required later. Senders don’t always know about your E-mail backlog and often send (75) messages.

A. too many B. redundant
C. long D. trivial

若某个直放站覆盖的范围内出现信号电平正常但掉话严重的情况，以为哪项是可能的原因（）

A、上下行功率不平衡

B、信源基站故障

C、干扰严重

D、切换不正常

E、天线不工作

F、隔离度不够