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【单选题】
序列x(n)的10点DFT为X(k) 0=A.
-1+j
B.
1-j
C.
1+j
D.
-1-j
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参考解析：
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皮皮学刷刷变学霸
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【单选题】将 xOy 平面内的椭圆 x^2/4+y^2/9=1 绕 y 轴旋转一周, 所得旋转曲面方程为
A.
x^2/9+y^2/4+z^2/9=1
B.
x^2/4+y^2/9+z^2/9=1
C.
x^2/9+y^2/4+z^2/4=1
D.
x^2/4+y^2/9+z^2/4=1
【单选题】What are types of condition disturbance?
A.
Refers to some types of noise which makes it possible to transmit message
B.
Refers to the major types of noise which makes it impossible to transmit message
C.
Refers to the noise which disturbs to transmit message
D.
Refers to all kinds of noise
【单选题】According to the passage, what is believed to cause the thin lines seen on Europa's surface?
A.
A long period of extremely high tides
B.
Water breaking through from beneath the surface ice
C.
The continuous pressure of slush on top of the ice
D.
Heat generated by the hot rocky core
【单选题】听力原文： A dictionary lists the words of a language, usually arranged in alphabetical order, but sometimes also by topic, with their meanings or their equivalents. The first important contribution to lex...
A.
The American Spelling Book.
B.
Compendious Dictionary of the English Language.
C.
An American Dictionary of the English Language.
D.
Webster's International Dictionary.
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