题干

关于竖直放置的肥皂液形成的薄膜干涉,下述说法中不正确的是(      )

A:干涉条纹的产生是由于光在膜的前后两表面反射,形成的两列光波叠加的结果

B:干涉条纹中的暗纹是由于上述两列反射光的波谷与波谷叠加的结果

C:干涉条纹是一组等间距的平行线

D:观察薄膜干涉条纹时,应在入射光的同一侧

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B

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    For years I wanted a flower garden. But then we had Matthew. And Marvin. And the twins, Alisa and Alan. And then Helen. I was too busy raising them to grow a garden.

    Money was limited, as well as time. Often when my children were little, one of them would want something that cost too much, and I’d have to say, “Do you see a money tree outside? Money doesn’t grow on trees, you know.”

Finally, all five got through high school and college and were off on their own. I started thinking again about having a garden. I wasn’t sure, though, I mean, gardens do cost money.

    Then, one spring morning, on Mother’s Day, I was working in my kitchen. Suddenly, I realized that cars were tooting their horns as they drove by. I looked out of the window and there was a new tree, planted right in my yard. I thought it must be a weeping willow, because I saw things blowing around on all its branches.

    There was a money tree in my yard !It was true! There were dollar bills, one hundred of them, taped all over that tree. There was also a note attached: “IOU eight hours of digging time. Love. Marvin.”

    Marvin kept his promise, too. He dug up a nice ten-by-fifteen foot bed for me. And my other children bought me tools, ornaments, a trellis, a sunflower stepping stone and gardening books.

    That was three years ago. My garden’s now very pretty, just like I wanted. When I go out and weed or tend my flowers, I don’t seem to miss my children as much as I once did. It feels like they are right there with me. I think about what my children did for me, and I get tears in my eyes every time.

    I’m still not sure that money grows on trees. But I know love does!