有甲、乙、丙、丁四个小组进行拔河比赛．比赛结果是：
①当甲、乙两组联合为一方，丙组和丁组为一方时，双方势均力敌；
②当甲组和丙组对调后．甲、丁两组联合战胜了乙、丙两组：
③甲、丙两组联合却被乙组单独一方战胜。
下列关于甲、乙、丙、丁四个组由强到弱的排序正确的是( )。

A．甲、乙、丙、丁

B．丙、乙、丁、甲

C．乙、甲、丙、丁

D．丁、乙、甲、丙

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. toomanyB. redundant C. long D. trivial