【简答题】已知随机变量ξ服从正态分布N(0, ),若P(ξ>2)=0.023,则P(-2 ξ 2)=
【简答题】在理想导体的表面,电场强度的 (切向/法向) 分量等于零。
【单选题】在理想导体表面上,电场强度的()分量为零,磁感应强度的()分量为零
【单选题】He often makes big plans that never ________. [ ]
【简答题】A.substance B.matter C.thing D.happening
【简答题】已知随机变量X服从正态分布N(3,σ 2 ),已知P(X>4)=0.2,则P(2<X≤3)=( )。
【单选题】What's _____ that girl? She looks very sad. [ ]