导线不经过用电器而直接跟电源两极连接的电路叫____，它的危害是：____．

如图所示的杠杆，每个砝码重均为1牛顿，杠杆处于平衡状态，若在杠杆两边各减去一个砝码，则（　　）

Dear Kelly,

    Today is Friday. It's evening in Shanghai. I'm writing to tell you something about my life (生活).My mother is cooking. My father is watching sports news(新闻).My brother, Tim, is playing computer games. My little sister, Mary, is drawing. My dog Dick is taking my hat to me. He wants me to put it on and go out for a walk with him. He's a clever dog and he is often excited(兴奋的)to see me.

    Outside, I can hear cars and buses coming and going. Also there are some boys playing ball games. It's a noisy(吵闹的)but happy evening. Do you think so?

    What are your family doing now?

    Please write me soon.

Yours,

Daniel

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