问题 选择题

两个完全相同的圆柱形容器内分别盛有水和酒精(ρ>ρ酒精),将实心金属球甲浸没在水中,实心金属球乙浸没在酒精中,这时水和酒精对容器底部的压强相等,将甲、乙小球从液体中取出后,容器中的液体对底部的压强大小仍相等,则可以确定(  )

A.甲球的质量等于乙球的质量

B.甲球的质量小于乙球的质量

C.甲球的体积等于乙球的体积

D.甲球的体积小于乙球的体积

答案

取出实心球后,水和酒精对容器底部的压强相等,P=P酒精gh酒精gh酒精;又因为ρ>ρ酒精,所以h<h酒精

如果甲乙两球体积相等,放入实心球后,排开水和酒精的体积将相等,水和酒精升高的高度将相等,因为密度不同,所以此时的压强将不会相等;

如果甲球体积大,水升高的高度将大于酒精升高的高度,产生的压强也不会相等;

如果甲球体积小,水升高的高度将小于酒精升高的高度,此时产生的压强才有可能相等;

因为不知道甲乙两球的密度关系,所以无法判断其质量的大小.

故选D.

阅读理解

阅读理解。

     Fans often only see the good fame(名声)of famous people. They see the happy smiles and great success of

famous people. But usually they cannot see the hard work or the hours of practice behind the great success.

     Li Yundi, a great Chinese piano talent, talked with teens about his art and his job."Of course, the job is hard

work. You need to work hard to be professional. And you also have to play hundreds of concerts, meet fans,

and listen to critics(评论家)."

     In 2000, when Li Yundi was 18, he won the top prize at the Chopin International Piano Competition in

Poland. Li was the youngest and the first Chinese to win the prize. Born in Chongqing, Li began to play the

piano when he was seven. His parents spent all their money and bought a piano for him-a luxury (奢侈品) in

the 1980s in China. He worked hard. Every day, he played for eight hours or more at a piano school. He often

played even after school. Li still can't play a beautiful tune without careful preparation (准备). "You need to be

ready (有准备的) on stage (舞台)," Li said."People are waiting for you. Nobody knows whether (是否) you

have slept enough, whether you have some problems in your life. But you need to play great music for your

audience(听众).That's what they want to hear."

1. People often see ________ of the famous people.

 A. happy smiles

B. big success

C. hard work

D. both A and B

2.  Li Yundi began to learn to play the piano in ________.

A. 1980

B. 1982

C. 1989

D. 1993

3. How did Li practice playing the piano when he was a child?

A. He played the piano at a piano school every day.

B. He went to Poland to learn to play the piano.

C. He learned to play the piano by himself.

D. His parents taught him to play the piano.

4. Why could he win first prize in Poland?

A. Because he was a piano talent and he played very well.

B. Because he was the youngest pianist.

C. Because he often played after school.

D. Because he was from China.

5. The underlined word "You" refers to(指) ________.

A. the children

B. Li himself

C. the audience

D. the parents

多项选择题