题目

已知随机变量X的分布列为P(X＝i)＝(i＝1,2,3,4)，则P(2＜X≤4)等于( )A. B. C. D. 答案：【答案】B【解析】由题意可得，即可求出的值，再利用互斥事件概率的加法公式可得，据此计算即可得到答案，解得则故选阅读短文，并用括号中所给动词的适当形式填空． I'm busy working these days. I ____1____ (not receive) any news from my family since last Sunday. Now I ____2____ (send) an e-mail to them. My father ____3____ (tell) me to buy him a new TV set. He enjoys ____4____ (watch) TV plays. If I am free, I'll buy one for him. I think he will be very happy ____5____ (see) it.