问题 解答题

在两个袋内,分别装有编号为1,2,3,4四个数字的4张卡片,现从每个袋内任取一张卡片.

(Ⅰ)利用卡片上的编号写出所有可能抽取的结果;

(Ⅱ)求取出的卡片上的编号之和不大于4的概率;

(Ⅲ)若第一个袋内取出的卡片上的编号记为m,第二个袋内取出的卡片上的编号记为n,求n<m+2的概率.

答案

解:(Ⅰ)第一个袋内卡片分别为A1、A2、A3、A4

第二个袋内卡片分别为B1、B2、B3、B4

(A1B1) (A1B2) (A1B3) (A1B4)(A2B1) (A2B2) (A2B3) (A2B4)  (A3B1) (A3B2) (A3B3) (A3B4)(A4B1) (A4B2) (A4B3) (A4B4)共16种,

(Ⅱ)卡片之和不大于4,即小于或等于4的情况有:

(A1B1)、(A1B2)、(A1B3)、(A2B1)、(A2B2)、(A3B1)共6种,

则其概率P==

(Ⅲ)根据题意,满足n<m+2的情况共13种,分别为:

(A1B1)、(A1B2)、(A2B1)、(A2B2)、(A2B3)、(A3B1)、(A3B2)、(A3B3)、(A3B4)、(A4B1)(A4B2)、(A4B3)、(A4B4),

则其概率P=

判断题
阅读理解

阅读理解。

     Why should I teach my children history? That sounds like a stupid question to even ask. But, as I hear

different home schooling teachers discuss history, I get the idea that there may be different reasons for

teaching history. Let me briefly explain the three good reasons for studying history and two bad reasons

for studying history.

     The major reason I see for studying history is that we can learn from the past. I am convinced that the

world would be a much better place if more people understood the successes and failures of the past and

the things that made these successes and failures. However, as the unfortunately true statement goes "the

one thing we seem to learn from history is that we don't seem to learn from history." Perhaps at least in

teaching history, to my children I can do a small part in changing this.

     A second major reason for studying history is that it is hard to understand the current political climate

in the absence of an understanding of its historical context. We can- not even understand why we are and

where we are without history, much less (更不必说) try to figure out where we are going or how we

should get where we want to be.

     I teach my children history, for one more reason. I purchased a set of historical audio (录音机) tapes

for our children. My seven-year-old son listened to them over and over. It was my hope that he would

become inspired by the accomplishments of people like the Wright brothers to accomplish things by

himself. I think that it is good that we celebrate the accomplishments of people like Martin Luther King Jr.

if, in doing so, young people are called on to stand for the principles that he stood for and accomplish what

he accomplished. I also think that by studying people like Adolph Hitler, people can learn to stand against

the things that he stood for.

1. What message can we get from the underlined sentence in Paragraph 2?

A. Many people aren't clever enough to learn well from the past.

B. Many people fail to make good use of history and make the same mistakes.

C. Many people feel it hard to understand history.

D. Many people have no interest in studying history.

2. In Paragraph 3, the author shows that history is useful because _____.

A. it makes the current political situation go smoothly

B. it helps us realize the importance of historical events

C. it helps us understand why things are the way they are

D. it helps people accept the present situation where they live

3. Some historical figures are mentioned in the last paragraph to show _____.

A. people can be inspired to do good, while can also learn to fight against evil

B. people may also learn from bad historical figures

C. more celebrations should be held to honor their achievements

D. today's people can also achieve what they achieved

4. What would be talked about in the following paragraph?

A. How to teach history effectively.

B. Some negative reasons for studying history.

C. How to get more people to study history.

D. Some bad historical figures.

5. The main purpose of this passage is to _____.

A. inspire the parents to teach their children history

B. show the importance of history in politics

C. explain the reasons why children study history

D. introduce the writer's own way of teaching history