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【单选题】
人受不了的是:
A.
L=20dB的次声波
B.
L=140dB的声波
C.
L=1400dB的超声波
D.
ABC
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参考答案:
举一反三
【单选题】随机变量X服从标准正态分布N(0,1).若【图片】取值为0.1,0.3,0.5,0.7,0.9,则对应的【图片】值分别是:
A.
1.2816,0.5244,0,-0.5244,-1.2816
B.
-1.2816,-0.5244,0,0.5244,1.2816
C.
1.2816,-0.5244,0,0.5244,-1.2816
D.
-1.2816,0.5244,0,-0.5244,-1.2816
【多选题】若由n个随机变量构造的统计量服从χ^2分布,则需满足下列哪些要求() A 随机变量X_1,X_2,......,X_n相互独立 B X_i(i=1,2......,n)服从标准正态分布N(0,1) C 随机变量的和 服从χ^2分布 D 随机变量的平方和 服从分布 E 自由度是n+1 F 自由度是n
A.
随机变量X_1,X_2,……,X_n相互独立
B.
X_i(i=1,2……,n)服从标准正态分布N(0,1)
C.
随机变量的和 服从χ^2分布
D.
随机变量的平方和 服从分布
E.
自由度是n+1
F.
自由度是n
【单选题】The words 'make' and 'bus' are called ______ because they can occur unattached.
A.
derivational morphemes
B.
inflectional morphemes
C.
bound morphemes
D.
free morpheme
【简答题】阅读理解。 My name is Gina Miller. I'm an English girl. I'm 11. I'm in No 7 Middle School. And I'm in Class 3, Grade7. I have two good friends, Li Ying and Mike. Li Ying is a Chinese girl. Her hair is blac...
【简答题】Suggestopaedia believes that language learning can occur at a much faster rate than it is often expected if learners can make better use of their______ powers.
【单选题】随机变量X服从标准正态分布N(0,1).若【图片】取值为0.1,0.3,0.5,0.7,0.9,则对应的【图片】值分别是:
A.
-1.2816,-0.5244,0,0.5244,1.2816
B.
1.2816,0.5244,0,0.5244,1.2816
C.
1.2816,0.5244,0,-0.5244,-1.2816
D.
-7.2816,-0.5244,0,0.5244,7.2816
【单选题】设随机变量X服从标准正态分布N(0,1),则E(X )=
A.
2e -2
B.
2e²
C.
-2e²
D.
【简答题】Suggestopaedia believes that language learning can occur at a much faster rate than it is often expected if learners can make better use of their______ powers.
【单选题】In zones where earthquakes are known to occur, ______ construction techniques can significantly reduce the effects of seismic wave.
A.
to improve
B.
improving
C.
improved
D.
being improving
【单选题】Who can predict the misery that may ______ humankind?
A.
happen
B.
befall
C.
chance
D.
occur
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