【单选题】【消耗次数：1】
允许低于某一频率的信号通过的滤波器是（ ）。
①
高通滤波器
②
带通滤波器
③
低通滤波器
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相关题目
【单选题】
用一个截止频率为w1的低通滤波器和一个截止频率为w２的高通滤波器，构成一个带通滤波器，应当使（）。
①
二者串联，并且w1w２
②
二者并联，并且w1w２
③
二者并联，w1w２
④
二者串联，w1w２
随机题目
【单选题】
13.The children have left. It’s getting _______ now.
①
quiet
②
quieter
③
more quiet
④
. calmer
【单选题】
7.He______ her on her new dress without looking at it.
①
praised
②
B. enjoyed
③
complimented
④
cared
【单选题】
25.I prefer this chair to the other one. It’s ___________ .
①
comfortable
②
more comfortable
【单选题】
21.Children used to be quiet. Nowadays they seem to be much ____________.
①
more noisy
②
noisy
【单选题】
30. I prefer __________ to ___________.
①
to drive; be driven
②
to drive; rather than being driven
③
driving; being driven
④
being driven; drive
【单选题】
15.Let me know if you hear any _____ news.
①
farther
②
further
③
far
④
. the further
【单选题】
20. He has received many presents from admirers, from the_____ to the valueless..
①
precious
②
expensive
③
priceless
④
cheap
【单选题】
8.We have very much ______ your prompt attention to our request.
①
enjoyed
②
appreciated
③
liked
④
. reduced
【单选题】
17.Her_____ body language spoke much louder than her actual words.
①
graceful
②
. grateful
③
gracious
④
grand
【单选题】
16.Tom and Jerry both gave good reports, but Tom’s was_____.
①
best
②
the best
③
better
④
the better