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【多选题】
下面关于周期矩形脉冲信号的频谱说法正确的是( )A.
频谱是离散谱，谱线间隔为基波频率，脉冲周期越大，谱线越疏。
B.
各分量的大小与脉幅成正比，与脉宽成正比，与周期成反比。
C.
各谱线的幅度按 包络线变化，过零点为 。
D.
主要能量在第一过零点内。主带宽度为
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皮皮学刷刷变学霸
举一反三
【简答题】A．To follow the committee's ideas. B．To make decisions with the committee. C．To run the committee according to his own ideas. D．To elect the committee chairman himself.
【多选题】Academic committee is also called __________.
A.
program committee
B.
scientific committee
C.
paper committee
D.
organizing committee
【多选题】Academic committee is also called __________.
A.
program committee
B.
scientific committee
C.
organizing committee
D.
paper committee
【简答题】肾上腺皮质激素的分泌具有昼夜节律性,每日上午( )时为分泌高潮,随后逐渐下降,午夜( )时为低谷,这是由ACTH昼夜节律所引起的。
【单选题】The most important committee of the Privy Council is
A.
the judicial Committee.
B.
the prerogative committee.
C.
the statutory committee.
D.
the legislative committee.
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