题干

有两种轮胎,轮胎A花纹较小较浅,轮胎B花纹较粗较深,大汽车应选用____ 种轮胎.突然刹车时能量转化关系是____  ;若刹车时受到地面的摩擦阻力为1×103N,刹车痕长5m,刹车前的动能大于____ J.

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答案(点此获取答案解析)

B,机械能转化为内能,5000

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根据短文内容, 完成下列各题。

       A few days ago, I ran into(撞上)a stranger as he passed by. I said sorry to him, and he said, "Excuse me too, I wasn't even watching for you.” We were very polite, this stranger and I.  Then we went on our way after saying goodbye.

       Later in the kitchen at home, as I cooked our meal, my daughter Betty walked up to me, very quietly. When I turned around (转身), I nearly knocked her down  "Get out of the way!" I shouted angrily. She ran away, crying.

       That night, when I lay in bed, my husband said to me, “You were so rude to Betty. Go and look around on the kitchen floor, and you'll find some flowers there. Betty brought those for you. She picked them herself-pink, yellow, and your favourite blue.’’

       When I heard this, I thought deeply: While meeting with a stranger, I was calm and polite; but with my daughter, I was not patient.  I felt sad and tears began to fall.

       I quietly went to Betty's bed, "Wake up, my dear," I said. "Are these the flowers you picked for me?" She smiled, “I found them by the tree. I knew you'd like them, especially the blue.” I said, ‘‘I am so sorry that I treated (对待) you that way today." And she whispered(悄声地说), “Mommy, that's okay- I still love you anyway.’’ I kissed her and said, “I love you too and I do love the flowers.”

       That day Betty gave me a lesson on how to get along with each other in the family. I spent much time on work before and didn't realize how important family life was. I decided to do better in the future.