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【单选题】
设某信道具有均匀的双边噪声功率谱密度P n (f)=n 0 /2(w/HZ) , 在该信道中传输抑制载波的双边带信号,并设调制信号的频带限制在5kHz,而载波为100kHz,已调信号的功率为10kW。若接收机的输入信号在加至相干解调器之前,先经过一理想带通滤波器滤波。那么解调器输入端的信噪功率比为( ) 。
A.
2/n 0
B.
n 0
C.
.n 0 /2
D.
1/n 0
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参考答案：
举一反三
【单选题】- I wonder if I could use your dictionary? - ______
A.
Go on.
B.
Go ahead.
C.
Go up.
D.
Go away.
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【单选题】Television, which made its first serious appearance in 1939, did not become common until the early 1950s. Since then, millions of children 11 in front of the set, and many people now worry about the e...
A.
wish
B.
wishes
C.
with
D.
whisper
查看完整题目与答案
【单选题】Not until the boys were old enough to understand how commercials tried to promote consumption were they allowed to watch sports programs on commercial television. The basic motto of the household was ...
A.
They were never allowed to watch commercials.
B.
They often watch some nature and sports programs.
C.
They were only allowed to watch television in the evening.
D.
Whenever there was any chance, they were asked to play outside instead of sitting in front of television.
查看完整题目与答案
【简答题】Some local companies are great effort to ___ with foreign companies for a share of the market. (connect, combine, compete, compare)
查看完整题目与答案
【单选题】已知 298K 时,反应 4NH 3 ( g ) + 5O 2 (g) === 4NO(g) + 6H 2 O(l) Δ f G m θ /kJ · mol -1 -16.5 0 86 -237 可以判断此反应在 298K 和标准状态下
A.
自发进行
B.
不自发进行
C.
处于平衡状态
D.
难以判断
查看完整题目与答案
【单选题】Television, which made its first serious appearance in 1939, did not become common until the early 1950s. Since then, millions of children 11 in front of the set, and many people now worry about the e...
A.
reaches
B.
rich
C.
reached
D.
reaching
查看完整题目与答案
【判断题】Exploiting the great potentials in the huge domestic market, some local IT companies have grown into giants with a stunning market value.
A.
正确
B.
错误
查看完整题目与答案
【单选题】Some local companies are making great efforts to _____ with foreign companies for a share of the market.
A.
connect
B.
combine
C.
compete
D.
compare
查看完整题目与答案
【单选题】反应4NH3(g)+5O2(g)→4NO(g)+6H2O(l)在298K、100kPa进行时的反应焓变 ( )kJ。
A.
-12.39
B.
12.39
C.
-2.48
D.
2.48
查看完整题目与答案
【单选题】反应 3NO 2 (g)+H 2 O(g)→2HNO 3 (l)+NO(g) 在298K、100kPa进行时的反应焓变 ( ) 。
A.
-2.48
B.
2.48
C.
-7.44
D.
7.44
查看完整题目与答案
相关题目：
【单选题】- I wonder if I could use your dictionary? - ______
A.
Go on.
B.
Go ahead.
C.
Go up.
D.
Go away.
查看完整题目与答案
【单选题】Television, which made its first serious appearance in 1939, did not become common until the early 1950s. Since then, millions of children 11 in front of the set, and many people now worry about the e...
A.
wish
B.
wishes
C.
with
D.
whisper
查看完整题目与答案
【单选题】Not until the boys were old enough to understand how commercials tried to promote consumption were they allowed to watch sports programs on commercial television. The basic motto of the household was ...
A.
They were never allowed to watch commercials.
B.
They often watch some nature and sports programs.
C.
They were only allowed to watch television in the evening.
D.
Whenever there was any chance, they were asked to play outside instead of sitting in front of television.
查看完整题目与答案
【简答题】Some local companies are great effort to ___ with foreign companies for a share of the market. (connect, combine, compete, compare)
查看完整题目与答案
【单选题】已知 298K 时,反应 4NH 3 ( g ) + 5O 2 (g) === 4NO(g) + 6H 2 O(l) Δ f G m θ /kJ · mol -1 -16.5 0 86 -237 可以判断此反应在 298K 和标准状态下
A.
自发进行
B.
不自发进行
C.
处于平衡状态
D.
难以判断
查看完整题目与答案
【单选题】Television, which made its first serious appearance in 1939, did not become common until the early 1950s. Since then, millions of children 11 in front of the set, and many people now worry about the e...
A.
reaches
B.
rich
C.
reached
D.
reaching
查看完整题目与答案
【判断题】Exploiting the great potentials in the huge domestic market, some local IT companies have grown into giants with a stunning market value.
A.
正确
B.
错误
查看完整题目与答案
【单选题】Some local companies are making great efforts to _____ with foreign companies for a share of the market.
A.
connect
B.
combine
C.
compete
D.
compare
查看完整题目与答案
【单选题】反应4NH3(g)+5O2(g)→4NO(g)+6H2O(l)在298K、100kPa进行时的反应焓变 ( )kJ。
A.
-12.39
B.
12.39
C.
-2.48
D.
2.48
查看完整题目与答案
【单选题】反应 3NO 2 (g)+H 2 O(g)→2HNO 3 (l)+NO(g) 在298K、100kPa进行时的反应焓变 ( ) 。
A.
-2.48
B.
2.48
C.
-7.44
D.
7.44
查看完整题目与答案
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