问题
填空题
氢气球释放后，若它的运动可看成是匀速上升，则上升过程中氢气球的动能_____（填“增大”“不变”或“减小”，以下空格同），重力势能_____，机械能_____．
答案
不变；增大；增大
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氢气球释放后，若它的运动可看成是匀速上升，则上升过程中氢气球的动能_____（填“增大”“不变”或“减小”，以下空格同），重力势能_____，机械能_____．
不变；增大；增大
One cold afternoon a postman was slowly pushing his mail cart (邮车)____the hill that led out of the small town of lane.He was walking very____because there was a lot of ice on the____.He had only one more letter to deliver(传递), and this was for an old lady who lived at the____.Everybody____her “grandma”． She had lived alone____her daughter had____to Hawaii many years before.She used to invite the postman____for coffee whenever he____her letter, and she would tell him about her two grandchildren in Hawaii，whom she had____seen.However, she had lots of____of them, which she used to____him. Just as the____came near her gate，a small boy came____down the hill.Suddenly the boy slipped on the ice and fell.The postman stopped his mail cart and hurried____the street to help the boy.After a quick____，he saw that he had hurt his leg very badly.In fact, he was____that the boy's leg had been broken. He knew that “grandma” did not have a____，so he stopped a____driver and asked him to____the boy to Lance Hospital.
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