问题 选择题

如图所示是安装在列车车厢之间的摩擦缓冲器结构图。图中①和②为楔块,③和④为垫板,楔块与弹簧盒、垫板间均有摩擦。在车厢相互撞击使弹簧压缩的过程中

A.缓冲器的机械能守恒

B.摩擦力做功消耗机械能

C.垫板的动能全部转化为内能

D.弹簧的弹性势能全部转化为动能

答案

答案:B

题目分析:由于楔块与弹簧盒、垫板间有摩擦力,即摩擦力做负功,则机械能转化为内能,故选项A错误,而选项B正确;[垫板动能转化为内能和弹性势能,故选项C错误;弹簧的弹性势能转化为动能和内能,故选项D错误。

阅读理解

When I was young, my father used to grow carnations — a kind of flower that was red, pink or white. He took care of them with much love and devotion. Every day he came home from work, he would enjoy watching them. And he used to tell us, “No one should touch my flowers.”

One day, my younger sister Clemence, who loved dad very much, wanted to help him. So she cut the carnation from their stems(枝干)one by one and arranged them on the ground. She believed that dad would be very pleased to see them that way.

When mom and I realized what my sister had done, we became completely speechless. However, my sister had no idea why no one showed her any appreciation. When dad arrived, he went as usual straight to watch the flowers. Seeing his flowers lying on the ground like dead animals, he was shocked at first. He looked towards the street to see if it was any of the neighbors’ children who could have done it. Then he looked at mom in silence. Finally mom, who always taught us to tell the truth no matter what, said, “No bad neighbors did this great job, only your lovely daughter Clemence.”

Dad’s face changed into a smile and then he said, “Do I have better flower than my lovely daughter?” My younger sister smiled and hugged(拥抱)dad strongly.

小题1:How did Clemence feel when she had the carnations cut?

A.Lucky.

B.Helpful.

C.Upset.

D.Worried.小题2:Which of the following is TRUE according to the passage?

A.No one knew what my sister had done with the carnations.

B.My younger sister told my father the truth about the carnations.

C.Dad had thought one outsider had cut the flowers from the stems.

D.Dad asked my sister to help arrange the carnations on the ground.小题3:What caused my younger sister to smile and hug dad strongly?

A.Mom’s help.

B.Mom’s words.

C.Dad’s silence.

D.Dad’s love.小题4:Which of the following would be the best title for the passage?

A.My Neighbors

B.Telling the truth

C.Growing Carnations

D.Dad’s Best Flower

多项选择题