题干

同温同压时,由CO2.N2和CO组成的混合气体的密度是氢气的15倍,则该混合气体中CO2.N2和CO的体积之比可能为                                                   (   )

A:1︰8︰2

B:2︰1︰13

C:4︰8︰2

D:15︰14︰1

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答案(点此获取答案解析)

B

同类题5

    On my eighth birthday, Dad bought me an accordion(手风琴) and said excitedly, "Once you learn to play, it'll stay with you for life." But I didn't want to play it. Ijust wanted to play games, But Dad asked me to take accordion lessons.
    One day, I found a box in a corner. When I opened it, I saw a beautiful violin. "You're your father's," Mum said. "His parents bought it for him. I guess he got too busy on the farm to learn to play it."
     I had to practice half an hour every day, and every day I tried to get out of it. But Dad didn't allow. I asked why. He answered, "Because you can bring people joy. You can touch their hearts." He added softly, "Someday you'll have the chance I never had: you'll play beautiful music for your family. And you'll understand why you've worked so hard." I was speechless.
    The lessons stopped after I finished high school. When I grew up, I got married and moved into a new house. I put the accordion in the attic(阁楼).
    One afternoon, my two children found the accordion by accident (偶然). They got very excited. "Play it. Play it," they laughed and said. I started to play some simple songs. I was surprised I could still remember them. Soon the kids were dancing. Even my wife was laughing and clapping to the beat.
    At that moment, my father's words came back to me, "Someday you'll have the chance I never had. And you'll understand." I finally knew why Dad had asked me to practice hard. Dad never learnt to play his violin. But I told my family, "This is my father's music."