【简答题】阅读下面短文,简要回答所给问题。 It was near Christmas during my first semester teaching at a new school.I loved my small special class more than any group I had taught in the past.They were hungry for knowledge and ...
【单选题】一座大厦如果有了白蚁,不加防治,不到十年时间,里面的地板壁板,都会蛀蚀一空。
A.
If a tall building is infested with termites and nothing is done about it, the floor and the wooden paneling inside it will have been eaten in less than ten years.
B.
The floor and the wallboard of a tall building will be eaten up by termites in less than ten years if the termites are not killed.
【简答题】设随机变量X的分布律为 ,求X的数学期望E(X).
【单选题】微机型变压器纵差保护中,设备差动速断保护的主要原因是( )。
B.
为了防止在区内发生严重故障时,由于电流互感器的饱和,二次电流严重畸变,导致受涌流闭锁的差动元件不能动作,延缓故障切除时间
【判断题】实际生产中,对薄壁件砂型铸造时应按“慢-快-慢”的原则浇注。
【单选题】一患者以颞下颌关节弹响就诊,检查发现此弹响为开口末闭口初,侧方运动和前伸运动无弹响,X线片显示为髁状突开口位时超过关节结节,你认为该病人是
【简答题】设随机变量X的概率密度为, (1) 随机变量X与函数|X|是否不相关? (2) 随机变量X与函数|X|是否相互独立?设随机变量X的概率密度为 f(x)=1/2*e^(-|x|),-∞ , (1) 随机变量X与函数|X|是否不相关? (2) 随机变量X与函数|X|是否相互独立?