干粉灭火机驱动气瓶内气体的总重量减少()以上时应立即补充.
A、1/5
B、1/10
C、1/20
参考答案:C
—Maria is wanted on the telephone. Where is she?
—She ______ the library. You can find her there. [ ]
A. has been to
B. has gone to
C. has left
D. has been in
gPON支持ATM和()&NbsP;两种模式。