问题 单项选择题

“总线忙”信号由 建立。

A.总线控制器
B.获得总线控制权的设备

C.CPU
D.发出“总线请求”的设备

答案

参考答案:B

解析:

[分析]:
本题考查总线控制信号的相关知识。
总线是计算机设备间用于传输数据的连线。在计算机中,从中央处理器到外设,总线可以分为4类,分别是中央处理器内部总线、部件内总线、系统总线和外总线。总线是否可以进行数据传输是由获得总线控制权的设备决定的,它通过“总线忙”信号和“总线闲”信号来实现对总线的占用和释放。

阅读理解

阅读理解。

     Long long ago the Mouse King had a beautiful daughter. When she was old enough to be married,

he called together the oldest and cleverest mice to talk about it.

     "My daughter," He said, "is far too beautiful to marry just anybody. I have decided to marry her to

the greatest thing in the world. Now, who shall it be?"

     "The sun," the first mouse said at once,  "is the greatest thing in the world. It shines over the whole

world. "

     "Why, then, I shall marry her to the sun," said the Mouse King.

     "But," said the second, "a cloud can cover the sun. "

     "Then, she must be married to the cloud. "

     "But," said the third, " the rain breaks through the clouds and puts an end to them. "

     "That is true. I must marry her to the rain. "

     "But," cried the fourth, "no matter how hard the rain falls, it cannot wash away the trees. "

     "Then she must be the tree's wife. "

     "But," shouted the fifth, "a strong wind can blow down the trees. "

     "Very true. Then the wind must be her husband. "

     "But," remembered the sixth,"  no matter how hard the wind blows, it cannot blow away the earth. "

     "Then I must marry her to the earth. "

     "But," called out the seventh," the earth is covered by the wooden floors of men's houses. "

     "Then she shall marry the wooden floor at once. "

     "But," the last said slowly, "no matter how strong the wooden floor is, a mouse can bite his way

through it. "

     "It is clear that a mouse is the greatest thing in the world," the happy Mouse King said, with a smile

on his face.

     And that was why the Mouse King's daughter married a mouse at last.

1. How many mice are mentioned in the passage?

A. Eight

B. Nine

C. Ten

D. Three

2. Which mouse had a beautiful daughter?

A. The old one

B. The cleverest one.

C. The first one

D. The Mouse King.

3. Who thought the wind should be the daughter's husband?

A. The second mouse

B. The fourth mouse.

C. The fifth mouse

D. Both A and C.

4. What was the result?

A. There was no result.

B. All those would be the daughter's husbands.

C. The daughter would be married to a mouse.

D. The daughter would live alone.

5. Why was the result so?

A. Because all the mice agreed.

B. Because all the mice wanted to have a rest.

C. Because the Mouse King thought a mouse was the greatest thing in the world.

D. Because the daughter was glad.

单项选择题