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搜题
【单选题】
Which of the following people would psychologists certainly consider to be shy?A.
A person who prefers to study alone rather than spend time with friends.
B.
A person who is afraid to talk to an attractive person of the opposite sex.
C.
A person who isn't good at introducing themselves to new people.
D.
A person who feels exceptionally nervous when around unfamiliar people.
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皮皮学刷刷变学霸
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【单选题】x∈D时函数p(x) =sin(x),否则p(x)=0,如果p(x)是一个随机变量的概率密度函数,那么区间D可以是下面的()
A.
[0，兀]
B.
[0，兀/2]
C.
[-兀/2，兀]
D.
[0，3兀/2]
【单选题】一个随机变量的概率密度函数是f(x),当x∈[0,1]时f(x)=1/3;当x∈[3,6]时f(x)=2/9;x在其他范围时f(x)=0。如果存在一个常数k使得概率P{X≥k}=2/3,则k的取值范围是()
A.
[0，3]
B.
[1，3]
C.
（2，3）
D.
[0，6）