搜题请搜索小程序“爱下问搜题”
问题 选择题
从甲口袋内摸出一个白球的概率是
1
3
，从乙口袋内摸出一个白球的概率是
1
2
，从两个口袋内各摸1个球，那么概率为
5
6
的事件是（　　）
A．两个都不是白球
B．两个不全是白球
C．两个都是白球
D．两个球中恰好有一个白球
答案

∵从甲口袋内摸出一个白球的概率是

1
3
，从乙口袋内摸出一个白球的概率是
1
2
，

故两个球全是白球的概率为

1
3
×
1
2
=
1
6
，

故两个球不全是白球的概率为 1-

1
6
=
5
6
，

故选B．

问答题 简答题

请说出高速公路10出口种特殊事件？
查看答案
填空题


The United States counts its population every ten years, and each census reveals that the racial and ethnic mix is changing dramatically, so by the year 2050, the "average" American will not be descended from (1) , but the majority of U. S. residents will trace (2) ancestry to Africa, Asia, the Hispanic world, the Pacific Islands, or the Middle East. Once the United States was a microcosm of European nationalities, (3) the United States is a microcosm of the world. The United States is (4) considered a "melting pot" society by many of its residents. (5) , many people prefer the term "salad bowl." They use this (6) to describe American society. American society will soon be (7) nonwhite. "Melting pot" implies that the different ethnic groups blend together (8) one homogeneous (9) , "salad bowl" (10) that nationalities, like the ingredients in a mixed green salad, retain their cultural (11) . Earlier generations of (12) believed they had to learn English quickly not only to survive but also for (13) .
Now, many immigrant groups do not (14) the same need. Because there are many places in America (15) you can work, shop, get medical care, marry, divorce and die without knowing English. (16) , Chinatown in San Francisco and New York. Also, Los Angeles has many Vietnamese immigrants and immigrants from Mexico. (17) , many immigrant groups want their children to know their (18) culture. Many Hispanics, for instance, want their children to learn (19) English and Spanish and study the Spanish language in school. They are fighting for the (20) to bilingual education in many communities. In many communities they are in the majority.
查看答案