管理单元指针位于STM-N帧中第4行的9×N列，共（）个字节.
A.1×N
B.4×N
C.9×N
D.4×9×N
参考答案：C
—_______ do you go to the English corner to practice your spoken English?
—Never. [ ]
A. How long
B. How often
C. How soon
D. How much
地铁火灾扑救中，为减少前线人员体力消耗，一般实施接力疏散救人方法。（）
