题干

 如图1是元素周期表中的一部分,图2是硒原子的结构示意图,据图回答问题:

(1)图2中m的值为____ ,n的值为____ ;

(2)硒元素位于元素周期表中的第____周期,硒化钠的化学式为____ .

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答案(点此获取答案解析)

34,6,四,Na2Se

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阅读理解

    I've loved my mother's desk since I was just tall enough to see above the top of it as Mother sat doing letters. Standing by her chair, looking at the ink bottle, pens, and white paper, I decided that the act of writing must be the most wonderful thing in the world.

    Years later, during her final illness, Mother kept different things for my sister and brother. “But the desk,” she said again, “is for Elizabeth.”

    I never saw her angry, never saw her cry, I knew she loved me; she showed it in action. But as a young girl, I wanted heart-to-heart talks between mother and daughter. It never happened. And a gulf opened between us. I was “too emotional”. But she lived “on the surface”. As years passed and I had my own family, I loved my mother and thanked her for our happy family. I wrote to her in careful words and asked her to let me know in any way if she chose that she did forgive me. I posted the letter and waited for her answer. None came. My hope turned to disappointment, then little interest and, finally, peace—it seemed that nothing happened. I couldn't be sure the letter had even got to Mother. I only knew that I had written it, and I could stop trying to make her into someone she was not.

    Now the present of her desk told me, as she'd never been able to, that she was pleased that writing was my chosen work. I cleaned the desk carefully and found some papers inside—a photo of my father and a one-page letter folded and refolded many times. She had given me an answer in a way she chose. Mother, you always chose the act that speaks louder than words.