题干

下列说法正确的是(   )

A:能量耗散从能量转化角度,反映出自然界的某些宏观过程中能量不守恒

B:从微观的角度来看,气体的压强大小跟气体分子的平均动能和分子的密集程度有关

C:悬浮在液体中的颗粒越大,撞击颗粒的液体分子数就会越多,布朗运动也就越明显

D:一定质量的气体,在体积减小的过程中,外界对气体做功,气体的内能一定增加

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答案(点此获取答案解析)

B

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    Do you want to cure all the diseases in the world? It seems like an impossible job, but Priscilla Chan is trying really hard to achieve it.
Chan is a 32-year-old woman from the United States. Many people may know her as the wife of Mark Zuckerberg, the founder of Facebook. But Chan herself has done a lot to help people.
    Chan and Zuckerberg said in September they would give out $3 billion(20 billion yuan) in the next 10 years to help deal with all of the world's diseases. As a doctor, Chan was a big driver in this decision. “We hope that all of our children can live long and healthy lives in the future,” she said.
    Besides health, Chan also cares about children's education. Before becoming a doctor, Chan taught science to fourth and fifth graders at a school in California for a year. This year she started a project called The Primary School. It provides education for children from kindergarten to the twelfth grade.
    Chan herself knows how important education is to a child. She has a Chinese father and a Vietnamese mother. Her parents didn't receive much education. But they worked hard to make sure Chan and their other two daughters would have the best opportunities. Chan went to Harvard University in 2003 and now works as a doctor. “ I realized that I was so lucky to be what I was,” said Chan. “so now, I will try my best to help others. I hope they can also have their opportunities to reach their dreams and be what they would like to be.”