If you are hunting         chance to improve yourself in English, I think the English corner will be        ________smart choice.

A．a; a

B．a; the

C．the; a

D．the; the

下列是数据通信网日常维护的项目（）

A.主、备链路切换试验

B.病毒检测和清除

C.系统口令修改

D.系统数据备份