已选分类
理学数学
单选题
单选题设随机变量X的概率密度f(x)，则随机变量2X+3的概率密度为()．(C)2f(2x+3)．(D)f(2x+3)．
单选题This book should be well-recommended within the ______ of anyone who
has studied German for four years.
A. possession
B. competence
C. confidence
D. qualification
单选题设随机变量X与Y相互独立，且X服从标准正态分布N(0，1)，Y的概率分布为．记Fz(z)为随机变量Z=XY的分布函数，则函数Fz(z)的间断点个数为(A)0．(B)1．(C)2．(D)3．
单选题
单选题设，则F(x)为()．
单选题
单选题设区域D=(x，y)|-1≤x≤1，-2≤y≤2，则()A．0B．2C．4D．8
单选题The employer tried to {{U}}bully{{/U}} his employees from staging strikes
by threatening to close down the entire plant.
A. intimidate
B. integrate
C. ridicule
D. humiliate
单选题
单选题
单选题已知实数a，b，c满足，则______．A．1B．C．D．E．
单选题
单选题A是三阶矩阵，它的三个特征值是1、2、-1，则|A*+3I|=( )．
单选题若则a+b+c的值是______．
单选题
单选题
单选题若a，b，c成等比数列，a，x，b和b，y，c都成等差数列，且xy≠0，则的值为____．
单选题
单选题