问题 单项选择题

在研究下述运动时,能把物体看作质点的是()

A.研究空中跳水动作的跳水运动员

B.研究飞往火星的宇宙飞船最佳运行轨道

C.研究地球自转

D.研究一列火车通过长江大桥所需的时间

答案

参考答案:B

解析:研究跳水运动员在空中的跳水动作时,运动员的大小和形状不能忽略,不能看作质点,否则就无法研究他在空中的动作了.故A错误.研究飞往火星的火星探测器最佳运行轨道时,火星探测器的大小相对于运动的距离很小,故火星探测器可看作质点.故B正确.研究地球自转时,因为地面上各点的运动状态不同,故不能看做质点,选项C错误;研究一列火车通过长江大桥所需的时间,火车的长度不能忽略,故此时火车不能看做质点,故D错误.故选B.

填空题
阅读理解

阅读理解。

     My name is Dave.   I am not an only child. I have three brothers and two sisters.   Sometimes they play with me.

     I am studying in a middle school now, but I am not a good student. I often get into trouble in class. For example,

I sometimes talk with my classmates, or sleep on the desk. Yesterday I didn't finish my homework, so my teacher

called my mom, and my mom was very angry with me. I felt sorry about that, too.

     However, I still have fun at school. I like sports and I am a member of   the school football team now.   I am also

crazy about handcraft and I am good at it. I can make a lot of things by hand, like toys and models. Can you guess

my dream? I want to be an artist in the future.

     Next year, I will take the entrance exam (入学考试) to high school. I promise that I will work hard at my studies

and pass the exam. I also want to go to a good university and make my dream come true.

1. How many children are there in Dave's family?

A. Three.    

B. Four.      

C. Five.      

D. Six.    

2. Why was Dave's mother angry with him?

A. He was late for school.      

B. He didn't do his homework.    

C. He fought with other boys.    

D. He talked with his brothers.  

3. What does the underlined word "handcraft" mean in Chinese?  

A. 摄影  

B. 鉴赏    

C. 手工  

D. 收藏

4. What will Dave do next year?

A. Go to work.    

B. Go to a university.    

C. Make his own dream come true.

D. Take the entrance exam to high school.   

5. Which of the following is RIGHT?

A. The school life is boring for Dave.

B. Dave's brothers and sisters don't like him.

C. Dave wants to be an artist when he grows up.

D. The teacher told Dave's mom some good news on the phone.