Basketball is still a young game. It's over a hundred years old. In the winter of 1891, a certain college was having some trouble with its boy students. The weather was bad and the students had to stay indoors. As they couldn't play outdoors, they were unhappy, and some even got into fights from time to time.

　　Some of the teachers, at the college asked Dr. Naismith to invent a game so that the students might have something to play with. It was not easy to invent such a game because it had to be played indoors , and the court (球场) was not very large.

　　Dr. Naismith thought for a few days and invented a kind of ball game. It was a fast, wonderful game with much moving and passing of the ball. It was played between two teams. To make a score , the ball had to be thrown into the basket ten feet(英尺) above the floor on the wall . At each end of the court there was such a basket. At first, Dr. Naismith wanted to throw the ball into a box. As he could not find boxes of the right size, he had to use fruit baskets instead. That is how the game got its name.

1. How long is it since basketball was invented?

　　A. 1000 years                      　　　　　　　　　　B. More than 100 years

　　C. 1100 years                       　　　　　　　　　　D. Less than 100 years

2. The students felt unhappy because _______.

　　A. they had much homework to do

　　B. they often got into fights

　　C. they couldn't play outdoors 

　　D. they had little time to study

3. Who asked Dr. Naismith to invent a game?

　　A. Some students                    　　　　　　　　B. Some teachers

　　C. Some students' parents           　　　 D. Some of his friends

4. When a student ______ , he makes a score.

　　A. receives the ball.               　　　　　　

　　B. throws the ball to another student

　　C. runs quickly with the ball in his hand  

　　D. throws the ball into the basket

5. Which sentence is right?

　　A. Dr. Naismith had to use fruit to throw the ball.

　　B. It was easy to invent the game.

　　C. The students could go outdoors when the weather was bad.

　　D. The ball had to be thrown into the basket five feet above the floor.

--Where is Mary? I'd like to have a talk with her.

　　--She _______________the library. You can find her there.

　　A. has been to　　　　B. has gone to　　　 C. has left　　　D. will leave

Every object has weight. But the center of its weight is not always in the middle of the object. If the top of an object is heavier than its bottom, it will fall over easily. We say that its center of gravity is high. But if the bottom is heavier, it won’t fall easily. Then we say that its center of gravity is low.

Look at the first picture. This empty box must fall over, because its center of gravity (C) is not above the line of its bottom (AB).

Now look at the second picture. There is some heavy iron in the bottom of this box. It will not fall, because its center of gravity is above its bottom.

1.If the bottom of an object is ______ its top, it will fall over easily.

A. lighter than　　 B. heavier than　　 C. no heavier than　　  D. as heavy as

2.Please point out which box will not fall.

3.The main idea of the passage is _________.

A. why things fall over　　　　         B. a low center of gravity

C. a high center of gravity　　             D. that everything has weight