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【简答题】
已知题图6．4．10(a)所示框图中，vc(t)=cosωct，cΩ(t)=VΩmcosΩt，且ωc≥Ω，设滤波器的幅频特性分别如图(b)、(c)、(d)所示。若不考虑信号通过滤波器的时延并设检波器的检波系数kd≈1。试： (a)写出A点信号的数学表达式； (b)分别写出通过3个滤波器后B点和C点信号vD(t)的表达式并说明它们是什么信号。
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举一反三
【单选题】The money we raised for the homeless ______________ 2,000 dollars.
A.
added
B.
added to
C.
was added up
D.
added up to
【单选题】We have raised some money and heavy clothes for the survivors in the earthquake________ they can go through the coming winter safely．
A.
on condition that
B.
so that
C.
now that
D.
in that
【单选题】下述程序段的输出结果是 。 int num=0 ; while(num--<=2) printf("%d\n", num+=2);
A.
1 2 3
B.
2 3 4
C.
1 2
D.
2 3
【简答题】人员促销主要适合于消费者数量多、比较分散的情况下。()
【简答题】We were so excited about it. We raised enough money. We had a great business model. We even signed incredibly great Hollywood (8)_________ to join the company.
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