动态控制每步(),一个SACCH周期可以调节()
A、2dB;8dB
B、2dB;16dB
C、4dB;16dB
D、4dB;32dB
参考答案:B
The number of the students _____ to 1,000 and the classroom becomes crowded now. [ ]
A. was risen
B. has risen
C. is cut down
D. has cut down
Don't jump __________ the train.[ ]
A. in
B. at
C. on