问题
填空题
汽车匀速上坡时动能______，机械能_______。（填“变大”、“变小”或“不变” ）
答案
不变 增大
汽车沿斜坡向上匀速行驶的过程中，汽车的质量不变，速度不变，高度增大，动能不变，重力势能增大，机械能增大．
故答案为：不变；增大．
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汽车匀速上坡时动能______，机械能_______。（填“变大”、“变小”或“不变” ）
不变 增大
汽车沿斜坡向上匀速行驶的过程中，汽车的质量不变，速度不变，高度增大，动能不变，重力势能增大，机械能增大．
故答案为：不变；增大．
Many people think that Americans 21 their cars almost more than anything else. When 22__ people are fourteen years old, they want to have their __23_ cars. They don’t ask for a car from their 24__. So many of them work in _25_ time during their last year of high school to buy a car. Learning to 26 _ and getting a driver’s license may be one of the most exciting things in a young person’s life. Some people almost 27 _ go to a doctor when they are ill. But they will __28_ their cars to a garage as soon as they think there is a 29 . On Saturdays or Sundays some people may 30 most of their time washing and repairing their cars.
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