问题
问答题
设X1，X2，…，Xn(n＞2)相互独立且都服从N(0，1)，Yi=Xi=
(i=1，2，…，n)．求
P{Y1+Yn≤0)．
答案
参考答案：
[*]
搜题请搜索小程序“爱下问搜题”
设X1，X2，…，Xn(n＞2)相互独立且都服从N(0，1)，Yi=Xi=
(i=1，2，…，n)．求
P{Y1+Yn≤0)．
参考答案：
[*]
| 阅读理解。 |
| A pop singer has to work very hard to become popular. He must give the public what they really want and need, or he must find a new way of singing that will attract their attention. Even when he has succeeded and his records are sold everywhere, he can not relax. Then he must work harder than ever to remain popular, because there are always younger singers trying to become famous and to steal some of the popularity. The life of a successful pop singer isn't easy at all. He can only relax when he is alone, because everything he does is watched and reported in the special newspaper written for the fans. The fans are the most important people in the world for the singer. They buy his records, they go to his concert, and they make him rich and famous. But they can be very dangerous, too. Sometimes they do anything to get a souvenir (纪念品). They steal handkerchiefs, they tear off buttons, and they even cut off pieces of the unfortunate singer's hair. Many singers have been forced to ride (即兴表演). A pop singer has to pay a lot of money for clothes because he must always look smart and different. And what's more, he must always keep smiling. |
| 1. After a pop singer has succeeded, he still works hard to _______. |
[ ] |
| A. get money B. stay popular C. sell more records D. become famous |
| 2. It may be suggested (被暗示) from the passage that _______. |
[ ] |
| A. a pop singer is somewhat afraid of meeting his fans B. a pop singer is anxious to see his fans C. not all people may become pop singers D. the pop singers become famous easily |
| 3. A proper title for the passage might be "_______". |
[ ] |
| A. The Way to Become a Pop Singer B. The Fans of the Pop Singer C. The Success of the Pop Singer D. The Pop Singer |
| 4. A pop singer has a lot of clothes in order to keep himself _______. |
[ ] |
| A. smart and the same B. smart and different C. healthy and young D. rich and strong |