可以采用包络检波进行解调的是()
A.FM信号
B.AM信号
C.DSB信号
D.VSB信号
参考答案:B
位于胫骨内侧面中央的穴位有()。
A.中封
B.中都
C.蠡沟穴
D.膝关
E.曲泉
You _____ to town to see the film yesterday. It will be on TV tonight.
[ ]
A. didn't need to go
B. couldn't go
C. should not go
D. needn't have gone