题干

小雪同学在厨房帮妈妈做饭时观察到了一些现象,用所学物理知识进行了解释,其中解释不正确的是(   )

A:轻推案板,案板不动,是因为推力小于摩擦力

B:用刀切冻肉前先磨刀,是为了在压力相同时,减小受力面积,增大压强

C:抽油烟机是利用流体压强与流速的关系来排烟的

D:手盆的下水管处利用连通器的原理,可以有效地防止异味返回

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答案(点此获取答案解析)

A

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    During the war, my husband was stationed at an army camp in a desert in California. I went to live there in order to be1 him. I hated the place .I had never 2been so unhappy . My husband was ordered out on a long-term duty, and I was left in a tiny shack(棚屋) alone. The heat was3-almost 125 0F even in the shade of a cactus(仙人掌).4a soul to talk to . The wind blew non-stop ,and all the food I ate ,and the every air I breathed, were 5 with sand , sand , sand !

    I was so sorry for myself that I wrote to my parents. I told them I was 6 and coming back home. I said I couldn't stand it one minute longer. I7 be in prison! My father answered my8with just two lines-two lines that will always sing in my9- two lines that completely changed my life :

    Two men looked out from prison bars

    One saw the mud ,the other saw the stars

    I read those two lines10I was ashamed of myself. I made up my mind I would find out what was good in my present11 I would look for the stars.

    I made friends with the natives, and their12amazed me. They gave me presents of their favorite artworks which they had13to sell to tourists . I studied the delightful forms of the cactus . I watched for the desert sunsets, and14for seashells that had been left there millions of years ago when the desert had been an ocean15

    What brought about this16 change in me ? The desert hadn't changed ,17 I had . I had changed my18.And by doing so ,I changed an unhappy experience into the most amazing19of my life . I was excited by this new world that I had discovered I had looked out of my self-created prison and20the stars