【简答题】序列 x(n) = cos (3 π n) 的周期等于()
【判断题】We had no idea at all. He told us he was leaving the company. Was the news out of the blue?
【单选题】The news had no _______ on her.
【单选题】已知4点序列x(n)=cos(πn),n=0,1,2,3,该序列的4点DFT为X(k),则X(0)=( )
【单选题】(Paragraph 2) The whole nation was shocked by the news the next day, and psychologists had no answers to explain why these people didn’t help.
A.
Only people in New York heard about the murder.
B.
News about the murder traveled quickly.
C.
The murder was not shocking to psychologists.
【判断题】序列x(n) = sin(3πn/4) + cos(0.5πn)是周期序列。