问题 选择题

某一物体运动情况或所受合外力的情况如图所示,四幅图的图线都是直线,从图中可以判断这四个一定质量物体的某些运动特征.下列有关说法中正确的是(  )

A.甲物体受到不为零、且恒定的合外力

B.乙物体受到的合外力越来越大

C.丙物体受到的合外力为零

D.丁物体的加速度越来越大

答案

A、甲做匀速直线运动,加速度为零,根据牛顿第二定律,合力为零.故A错误.

B、乙物体做匀加速直线运动,加速度恒定,则合力恒定.故B错误.

C、丙物体加速度恒定,则合力恒定,且不为零.故C错误.

D、丁物体所受的合力逐渐增大,则加速度逐渐增大.故D正确.

故选D.

阅读理解

阅读理解。

      Mr Young worked in a factory.  He was an able (有能力的) worker and could get more money than

  his workmates.  His wife was able,  too.  She did all the housework and took good care of her

 children.  They were never worried about food or clothes.  But they were both miserly (吝啬) and tried to

  save everything.  Their family wore old and broken clothes.  He always went to work and their children

  went to school on foot.

    One afternoon, while Mrs Young was cooking supper, she heard the bell.  A man said on the

 telephone,  "I'm sorry to tell you something unlucky.  Your husband died in an accident. "

    The woman hardly believed her ears.  "When did it happen?" she shouted sadly.  "At four, Mrs Young. "

    "It's half past five!" the woman said angrily.  "Why didn't you tell me about it an hour ago? I've cooked

 supper for him ! "

     "Everything was confused (混乱的) here at that moment and all of us forgot it. "

     "What were his last words? "

     "He asked us to retell you he wouldn't go back for supper!"

1. Mr Young was able, so_____.

    A.  he wore old clothes            

    B.  he spend twenty to work on foot

    C.  he lived a happy life          

    D.  he got more money

2. Mr Young's children went to school on foot because_____.

    A.  they were poor

    B.  his parents tried to save money

    C.  there were no buses in the town

    D. they hoped to do morning exercises

3. Mrs Young began to cook supper at_____.

    A.  four      

    B.  half past four      

    C.  five      

    D.  half past five

4. The phrase "last words " in the story means_________.

    A. 最后一些词语            

    B. 最后一些话

   C. 遗言                    

    D. 嘱托

5. Mrs Young became angry because          .

    A. she wasn't told about the bad news before she cooked supper.

    B.  the factory didn't retell her husband's last words in time.

    C.  she couldn't see her husband before he died.

    D.  she didn't know whether her husband's last words were real.

多项选择题