下列生活实例中，属于减小摩擦的是（ ）
A．鞋底的花纹
B．向车的转轴处加润滑油
C．在结冰的路面上撒上煤渣
D．拔河时要用力抓紧绳子
A、鞋底的花纹是通过增大接触面的粗糙程度来增大摩擦力；
B、往车的转轴处加润滑油是减小接触面的粗糙程度来减小摩擦力；
C、在结冰的路面撒上煤渣是通过增大接触面的粗糙程度来增大摩擦力；
D、拔河时用力拉紧绳子是通过增大压力的办法来增大摩擦力的．
故选B．
| 阅读理解。 | |||||||||||||||||||||||||||
| Stress is everywhere in our everyday life. Not only men have it, but also women and young people. The most important reasons of stress are: death, diseases, exams, making money, getting married, moving houses, changing jobs, ending friendships and so on. How do you know whether you have stress? Could you give your answers to the following questions? Stress Test | |||||||||||||||||||||||||||
what can you do about it? Doing relaxing exercises, talking with friends and listening to light music are all usual ways of relieving (减轻) stress. However, doctors now say that there are easier ways-people should laugh and smile more often. When you laugh and smile, your body relaxes. They also say that people, especially men, should cry more often, because crying is the natural way of relieving stress. | |||||||||||||||||||||||||||
| 1. Which of the following is NOT the reason of stress? | |||||||||||||||||||||||||||
[ ] | |||||||||||||||||||||||||||
| A. Taking exams. B. Changing jobs. C. Taking sleeping pills. | |||||||||||||||||||||||||||
| 2. According to the passage,which of the following is true? | |||||||||||||||||||||||||||
[ ] | |||||||||||||||||||||||||||
| A. Only women and young people have stress. B. Stress is everywhere in our everyday life. C. People who answer"No" to all of the questions have great stress. | |||||||||||||||||||||||||||
| 3. Which is not the usual way of relieving stress? | |||||||||||||||||||||||||||
[ ] | |||||||||||||||||||||||||||
| A. Talking with friends. B. Listening to light music. C. Taking medicine. | |||||||||||||||||||||||||||
| 4. The easier way to relax your body is _____. | |||||||||||||||||||||||||||
[ ] | |||||||||||||||||||||||||||
A. Laughing,smiling and crying | |||||||||||||||||||||||||||
| 5. The main idea of the passage is _____. | |||||||||||||||||||||||||||
[ ] | |||||||||||||||||||||||||||
| A. about stress and how to relieve your stress B. that there are many reasons for having stress C. that laughing and smiling more can help relieve your stress |