题目内容

[音频]

A. It’s not as good as it was.
B. It’s better than people say.
C. It’s better than it used to be.
D. It’s not better than people say.

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[音频]

A. She agrees with the man.
B. She is wild, too.
C. She doesn’t agree with the man.
D. The man is wild, too.

白炽灯的额定工作电压为220V,它允许承受的最大电压为( )

A. 220V
B. 311V
C. 380V
D. 200V

正弦量的三要素是指( )。

A. 电阻、电感和电容
B. 有效值、频率和初相
C. 电压、电流和相位差
D. 瞬时值、最大值和有效值

周期T=1S、频率f=1Hz的正弦波是( )

A. 4cos314t
B. 6sin(5t+17°)
C. 4cos2πt
D. 4cosπt

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