题干

(1)列举出两种可再生能源.

(2)如图所示,小朋友沿着滑梯匀速下滑的过程中,动能和势能如何变化?下滑过程中为什么臀部觉得发热?

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答案(点此获取答案解析)

解:(1)风能、水能都属于可再生能源.

(2)匀速下滑时,速度不变,动能不变,高度下降,重力势能减小.

小朋友匀速下滑,重力势能减小,动能不变,克服摩擦力做功,内能增加,重力势能转化为内能,使温度升高,所以小朋友的臀部觉得发热.

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完形填空

    I learned to do wood work when I was very young. I remember I made my first project—a small table when I was 9 years old. I was so1of it that I looked upon it as if I had created a(an)2. It was absolutely beautiful and it had taken me six weeks to3it. I could hardly wait to give it to Mother Winters as a(an)4. She was the head mistress of our orphanage(孤儿院), who was always kind but5with us.

    As the tables were not dry from the clear coating(清漆), our woodworking teacher told us to wait a few days before taking them to our dormitories. But I was just so6and happy that I couldn't wait. I dashed out like a7, carrying my table, smiling from ear to ear.

    When I reached the dormitory I placed the little table beside my bed. I was8it when Mother Winters entered. She walked over to the table. Running her hand9it, she noticed that it was still wet.

    “Were you 10to bring this home?” she asked.

    “No, ma'am,” I 11with my head down.

    She ordered me to throw the table out and so I did. After she left, I immediately opened the door to get it back. There was 12stuck all over. I brushed and cried, but the dirt would not come off.

    I hid the table in my closet and never 13it. However, a year later during a cleaning-up, it was discovered. Painfully, I had to give the table to Mother Henderson, my houseparent, thinking that she would 14it away.

    Thirty years later at a reunion, I15that Mother Henderson was living nearby, so I drove up to see her. We talked cheerfully for a long time. As I was about to leave, she asked me to come down to her 16to get something important. I followed her 17into a dark corner. She picked something up.18she turned around, I could see that she was holding a little table. Mother Henderson kept the little table that I had given up for lost so long ago.

    Today, I look at that table with bittersweet memories but full of 19to Mother Henderson, who kept the table for a young orphan who20it so much.