— Do you think it's a good idea to make friends with your students?

— ________, I do. I think it's a great idea. [ ]

A. Really  

B. Obviously

C. Actually  

D. Generally

煤矿井下安全避险“六大系统”是指（）。

A．监测监控系统

B．井下人员定位系统

C．紧急避险系统

D．压风自救系统

E．供水施救系统

F．通信联络系统