题干

下列说法正确的是(   )

A:教室内的空气绝对湿度大,则空气的相对湿度一定大

B:上午十时,教室内空气中的水蒸气分子和氧气的分子平均动能是相同的

C:下雨时,观察教室屋檐滴下的水滴,发现水滴在下落过程中呈椭圆球形,这是表面张力

D:水中的水分子总是在永不停息地做杂乱无章的运动,当两个水分子运动到适当的位置使分子力为零时,它们具有的分子势能一定最小

E:一定质量的水蒸气发生等温膨胀时,可能会向外散热

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答案(点此获取答案解析)

B,C,D

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    I serve as an educator and health care provider as well, therefore, I have worked with numerous children infected with the virus that causes AIDS. The relationships that I have had with these special kids have been gifts in my life. They have taught me so many things, but I have especially learned that great courage can be found in the smallest of packages. Let me tell you about Tyler.

    Tyler was born infected with HIV: his mother was also infected.From the very beginning of his life, he was dependent on medications to enable him to survive.When he was five, he had a tube surgically inserted in a vein in his chest.This tube was connected to a pump, which he carried in a small backpack on his back. Medications were hooked up to this pump and were continuously supplied through this tube to his bloodstream.At times, he also needed supplemented oxygen to support his breathing.

    Tyler wasn't willing to give up one single moment of his childhood to this deadly disease.It was not unusual to find him playing and racing around his backyard, wearing his medicine-laden backpack and dragging his tank of oxygen behind him in his little wagon.All of us who knew Tyler marveled at his pure joy in being alive and the energy it gave him.Tyler's mom often teased him by telling him that he moved so fast that she needed to dress him in red.That way, when she peered through the window to check on him playing in the yard, she could quickly spot him.

    This dreaded disease eventually wore down even the likes of a little dynamo (精力充沛的人) like Tyler. He grew quite ill and, unfortunately, so did his HIV-infected mother.When it became apparent that he wasn't going to survive, Tyler's mom talked to him about death.She comforted him by telling Tyler that she was dying too, and that she would be with him soon in heaven.

    A few days before his death, Tyler beckoned me over to his hospital bed and whispered, “I might die soon.I'm not scared.When I die, please dress me in red.Mom promised she's coming to heaven, too.I'll be playing when she gets there, and I want to make sure she can find me.”