捻度的方向有Z捻和()捻两种。
A.Y
B.T
C.S
D.X
参考答案:C
My mother asked me______ enter my room.
A.whether she could
B.when could she
C.that she can
D.how can she
模拟调制主要的基本形式有()。
A.幅度调制(AM)
B.频率调制(FM)
C.相位调制(PM>
D.时间调制。