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【简答题】
信号f(t) 到f(at) 的运算中,若 a >1 ,则信号 的时间尺度 __________ a 倍。(扩展或压缩)
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皮皮学刷刷变学霸
举一反三
【单选题】________ these experiments were successfully completed would we think of going into humans.
A.
If only
B.
Only if
C.
So that
D.
Even if
【单选题】With the sun (setting), we stopped (working), (putting) away our tools and were (going) to go home.
A.
setting
B.
working
C.
putting
D.
going
【单选题】— How were things going that day? — We were really tired out. We _____ 10 hours before we got to the village. [ ]
A.
had walked
B.
were walking
C.
walked
D.
have walked
【简答题】Today we spent the morning going through our personal belongings .We were looking for items to __ for free at a local park. Not just any items but things people really . Our aim was not to find things...
【单选题】We used to _____every day when we were children.
A.
swim
B.
swimming
C.
be swimming
D.
going swimming
【单选题】We were going out for a walk ________ it began to rain.
A.
while
B.
before
C.
as
D.
when
【单选题】_____the wind and waves we were going in the direction of the whirlpool,and nothing could save us.
A.
By
B.
At
C.
To
D.
With
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