李宗仁指挥的自抗战以来中国军队取得重大胜利的一次战役是[ ]
A.平型关战役
B.百团大战
C.台儿庄战役
D.武昌战役
答案:C
– I think we can have a long time to relax this summer!
–______. We should get ready for high school.
A.I think so
B.I disagree
C.That sounds good
D.Good luck
假设X服从参数为λ的指数分布,对X作三次独立重复观察,至少有一次观测值大于2的概率为
,则λ=______.