【简答题】假设A与B为互斥事件,且P(A)0,P(B)0,试证事件A与B不相互独立。
【单选题】设事件A,B互斥,且P(B)>0,则下列各式中正确的是
【判断题】Jenny suggests Billy make a monthly finance plan.
【简答题】设A,B为两个事件,且已知概率P(A)>0,P(B)>0,若事件A,B互斥.则下列等式中( )恒成立. (a)P(A+B)=P(A)+P(B) (b)P(A+B)=P(A)P(B) (c)P(AB)=P(A)+_P(B) (d)P(AB)=P(A)P(B)
【单选题】晶体的电光效应指的是( )。
A.
某些晶体在外加电场的作用下,其折射率随外加电场的变化而变化的现象。
B.
某些晶体在外加电场的作用下,吸收系数随外加电场的变化而变化的现象。
C.
某些晶体在外加电场的作用下,反射率随外加电场的变化而变化的现象。
【判断题】一、二级耐火等级建筑的屋面板应采用不燃材料,但屋面防水层可采用可燃材料。
【简答题】Billy looks becaus he doesn't have enough money to .His mother has given him the money of this month, but he . Jenny suggests that he should for himself. Finally, Jenny lends to Billy.
【简答题】Billy looks __________ because he doesn't have enough money to __________ .His mother has given him the money of this month, But he __________ . Jenny suggests that he should __________ for himself. F...
【判断题】电光调制的物理基础是电光效应。电光效应是指如果在晶体中沿某一方向上加一定电压,则晶体的折射率要发生相应的改变,因而晶体的双折射特性也要发生改变。