PDH的二次群8Mbit/s信号采用如下（）容器装载。
A.C12
B.C2
C.C3
D.无对应容器
参考答案：D
To their great _____, Tom’s problem proved not to be as serious as they had feared.
A．happy
B．worry
C．anxiety
D．relief
在声音感受的过程中，最重要的振动膜是
A．鼓膜
B．前庭膜
C．蜗窗膜
D．基底膜
E．盖膜
