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【单选题】
设随机变量X与Y的方差均存在且不为0,若E(XY)=EXEY,则( ).A.
X与Y一定独立
B.
X与Y一定不相关
C.
D(XY)=DXDY
D.
D(X-Y)=DX-DY
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【简答题】The _______ of the accident received head injuries from which shedied a week later. A) victim B) vegetariant C) veteran D) variant
【单选题】Does something that happens periodically happen (a) from time to time, or (b) regularly every week?
A.
from time to time
B.
regularly every week
【单选题】Every morning, week in, week out, from dawn to dusk , he ______ his place on the bend.
A.
makes up
B.
picks up
C.
takes up
D.
turns up
【简答题】From next week Mike plans to run
【判断题】血红蛋白和呼吸酶是细胞内的蛋白质,不分泌到细胞外;胃蛋白酶原和唾液淀粉酶则是由附着在内质网上的核糖体合成,通过内质网和高尔基体加工运输到细胞外面的分泌蛋白。
A.
正确
B.
错误
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