卡特设备SDCCH拥塞率统计公式包含哪些counter（）
A.MC8d
B.P62a
C.P62c
D.MC8c
参考答案：A, C, D
—What's the problem with FM 96.8?
—I listen to it sometimes, just not every day. [ ]
A. shall
B. must
C. can
D. need
阐述PCR基本原理。
