问题 问答题

在杂技表演中,有一个项目叫做跳板,重量很小的表演者乙站在跳板左端,重量很大的演员甲从立好的支架上跳下,落在跳板的右端,这时乙会弹起,恰好落在另一表演者肩上扛的杆的座椅上,如下图所示。你能说明一下,跳板表演的物理根据是什么吗?为什么乙要比甲轻许多呢?

答案

重力势能和动能之间相互转化。乙比甲轻,质量小,弹起的高度更大些。

阅读理解

阅读理解。

     It is the first day of October today. It is my grandmother's birthday. Father, mother, sister and  I go to

 see her.

     First we go to a supermarket to buy some presents for my grandmother. My father buys a big cake (蛋

 糕). My mother buys a red sweater. My sister buys a green T-shirt.I buy a black hat for my grandmother.

 We go to my grandmother's home in my father's car. We get there at around nine o'clock. My

 grandmother is very happy to see us. We give these presents to her and say to her, "Happy birthday to

 you!,'My grandmother is very glad (高兴的).Then my sister and I sit down and play games with my

 grandmother. After dinner we say goodbye to her and go back (回) home. We are very happy today.

1.  My grandmother's birthday is _____.

    A. October thirty-first    

    B. October first

    C. October second    

    D. October third

2. My mother buys-for my grandmother.

    A.  a black hat    

    B.  a big cake    

    C.  a blue sweater    

    D.  a red sweater

3. We go _____ to buy some presents.

    A.  a clothes store    

    B.  a supermarket    

    C.  afruit shop    

    D.  a book store

4.  My grandmother is very _____ to see us.

    A. old    

    B. unhappy (不高兴)

    C. happy    

    D. boring

5. My sister and I play games with my _____.

    A. mother    

    B. uncle    

    C. grandmother    

    D. father

解答题