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【单选题】
慢性根尖周炎属于哪一种病变类型A.
致密性骨炎
B.
根尖肉芽肿
C.
根尖囊肿
D.
根尖脓肿
E.
有瘘性根尖脓肿
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反馈参考答案：
举一反三
【简答题】设随机变量 X1,X2 相互独立,且 X1 服从二项分布 B(20, 0.7); X2 服从 的泊松分布 P(3)。记 Y = X1 – 2 X2 + 2,则 E(Y) = ; D(Y) = .
【单选题】Stay here, boy. Don’t go out. It now.
A.
will rain
B.
is going to rain
C.
has rained
D.
is raining
【单选题】Is there _______ here? If not, don't stay here alone. [ ]
A.
anyone
B.
somebody
C.
anyone else
D.
everyone
【简答题】设随机变量x1 x2,相互独立,且x1服从二项分布B(20,0.7);X2服从 λ=3的泊松分布P(3)。记y=X1-2*X2+2则E(X)=(),D(Y)=()
【简答题】Stay here, boy. Don't go out.It _____(rain) now.
【单选题】Is there _____ here? If not, don't stay here alone. [ ]
A.
anyone
B.
someone
C.
anyone else
D.
everyone else
【单选题】Pushing sequence is {1,2, ⋯ ,100}.In popping sequence,before 10,there are four numbers larger than 10 .Which one cannot be popped out before 10.
A.
5
B.
6
C.
14
D.
15
【简答题】设随机变量X1, X2相互独立,且X1服从二项分布B(20, 0.7);X2服从l=3 的泊松分布P(3)。记Y=X1-2X2+2,则E(Y )=__________;D(Y )=_________。
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