1Np=（）dB。

[单选题]已知二项分布的数学特征为:E(x)=np,s(x)=np(1-p)。如果随机变量x~B(10,0.3),则E(x),s(x)分别为()。A .3,2.1B .3,3C .0.3,3D .0.3,2.1

[试题]3) 0dB的含义是_______________？1W＝_________dBm。

[单选题]已知L1=85dB，L2=85dB，则合成声压级L1+2是（）dB。A . 86B . 87C . 88D . 90

[单选题]已知L1=56dB，L2=56dB，则合成声压级L1+2是（）dB。A . 57B . 58C . 59D . 60

[单选题]器件RD-52N/NP-F1的工作频带是（）A .890~909MHzB .890~960MHzC .800~2400MHzD .1710~2300MHz

[填空题] 在声学中，一个量与同类基准量之比的对数称为级。常用的级的单位是dB（分贝）或NP（奈培）。INP=（）dB。

[名词解释] NP完全问题

[单选题]The notion of NP-completeness has provided a(66)mathematical definition for(67)intractability of NP problems. But this measure applies only to worst-case complexity. Being NP-complete does not(68)that a problem is intractable on the average case. Ind

[单选题]NP and ( ) are essential components of a sentence.A.VPB.PPC.APD.all of the

[单选题]NP and ( ) are essential components of a sentence.A.VPB.PPC.APD.all of the