问题 选择题

沿着高度相同,坡度不同,粗糙程度也不同的斜面向上拉同一物体到顶端,以下说法中正确的是(  )

A.沿坡度小,长度大的斜面上升克服重力做的功多

B.沿长度大、粗糙程度大的斜面上升克服重力做的功多

C.沿坡度大、粗糙程度大的斜面上升克服重力做的功多

D.上述几种情况重力做功同样多

答案

解析:重力做功只与高度有关,与路径无关,又斜面的高度相同,因此,题中所述几种情况重力做功同样多.故ABC错误,D正确.

故选D.

阅读理解

Jack is a twenty-year-old young man. Two years ago, when he finished middle school, he found work in a shop. Usually he works until ten o'clock in the evening. He is very tired when he gets home. After a quick supper he goes to bed and soon falls asleep. His grandma who lives downstairs is satisfied with (满意) him.

  One day, on his way home, he met Mary. They were both happy. He asked the girl to his house, she agreed happily. He bought some fruit and drinks for her. And they talked about their school, teachers, classmates and their future (未来). They talked for a long time.

  "Have a look at your watch, please," said the girl. "What time is it now?"

  "Sorry, something is wrong with my watch," said Jack. "Where's yours?"

  "I left it at home."

  Jack thought for a moment and found a way. He began to stamp his foot on the floor, "Bang! Bang! Bang!"

  The sound woke his grandma up. The old woman shouted downstairs, "It's twelve o'clock in the night, Jack. Why are you still jumping upstairs?"

小题1:Jack was ________ when he finished middle school.

A.sixteen

B.eighteen

C.twenty

D.fifteen小题2:The old woman is satisfied with Jack because ________.

A.he's her grandson

B.he's clever

C.he can keep quiet

D.he gets home on time小题3:From the story, we can know that Mary is Jack's ________.

A.classmate

B.colleague (同事)

C.aunt

D.wife小题4:The word "stamp" in the story means ______ in Chinese.

A.盖印

B.跺

C.贴邮票

D.承认小题5:Jack stamped his foot on the floor in order (为了) ________.

A.to wake his grandma up

B.to make his grandma angry

C.that his grandma was going to tell him the time

D.that his grandma was going to buy him a watch

单项选择题