问题 选择题

下面有关机械能和内能的说法中正确的是(   )

A.机械能大的物体,内能一定也大

B.物体做加速运动时,其运动速度越来越大,物体内分子平均动能必增大

C.物体降温时,其机械能必减少

D.摩擦生热是机械能向内能的转化

答案

答案:D

机械能与内能有着本质的区别,对于同一物体,机械能是由其宏观运动速度和相对高度决定的,而内能是由物体内部分子无规则运动和聚集状态决定的。答案:D

阅读理解

阅读理解

Today almost everyone knows computers and the Internet. If I ask you “What is the most important in your life?” maybe you will say “Computers and the Internet.”

The first computer was made in 1946. it was very big but it worked slowly. Today computers are getting smaller and smaller. But they work faster and faster. What can computers do? A writer has said, “People can’t live without computers today.”

The Internet came a little later than computers. It is about twenty-five years later than computers. But now it can be found almost everywhere. We can use it to read books, writer letters, do shopping, play computer games or make friends.

Many students like the Internet very much. They often go into the Internet as soon as they are free. They make friends on the Internet and maybe they have never seen these friends. They don’t know their real names, ages, and even sex. They are so interested in making the “unreal friends” that they can’t put their hearts into study. Many of them can’t catch up with others on many subjects because of that.

We can use computers and the Internet to learn more about the world. But at the same time, we should remember that not all the things can be done by computers and the Internet.

小题1: The Internet can not be used for______.

A.studying

B.shopping

C.thinking

D.playing小题2: When the computer was invented, it was______.

A.large and worked quickly

B.small and worked slowly

C.large but worked slowly

D.small but worked quickly小题3: The Internet was born in about________.

A.1960

B.1970

C.1980

D.1985小题4:Which of the following is TRUE?

A.Few students like going into the Internet.

B.Students use the Internet to make “unreal friends.”

C.These “Unreal friends” often meet each other

D.Students know the friends on the Internet very well小题5:What does the writer think of the Internet?

A.It is wonderful

B.It can make students study harder

C.It is not good for students

D.It is helpful, but we can’t do everything on it.

问答题 简答题