题干

如图所示,一带电粒子沿与电场线垂直的方向从电场中央进入两平行金属板间的匀强电场,已知粒子的带电量为q,两板间的电势差为U,则粒子运动过程中(  )

A:若粒子从电场中射出,则粒子动能增加了qU

B:若粒子从电场中射出,则电场力一定对粒子做了qU/2的功

C:若粒子打在极板上,则电场力一定对粒子做了qU/2的功

D:若粒子打在极板上,则粒子的动能一定增加了qU

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C

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    Jack was born without eyes. He's very lucky with his timing. He grew up having other kittens to play and socialize with, and was used to people from the moment he was born since there are always kids hanging around the barn. He was a favorite amongst the students at the barn. However, when it came time to find the kittens homes, no one knew where Jack would end up. That's when I got an e-mail from my friend. All she asked was “Do you still want one of the kittens? There's one here with no eyes and no one can take him.” Without thinking I told her that I did want the kitten.

    When we first brought him home Jack stayed mostly in my room. He walked cautiously around, sniffing everything. After about a day he had no issues running around, jumping onto my bed and climbing on everything. He went through a time where he could climb the stairs, but couldn't get down. He would sit at the top and cry until someone came and got him. Every now and then when he gets disoriented he'll stop and cry. But we just call his name and talk to him and it isn't long before he finds his way back to us.

    Also, a few weeks after getting Jack, we got a new barn cat named Bear. I always take Jack outside at that time for some fresh air and exercise. He loves to run (at top speed!) around the back yard and gardens. Bear and Jack have become best friends. It doesn't matter that he can't see, Jack always knows when Bear is around. He'll run across the yard straight to Bear and wrap his front legs around his neck in a big hug. They chase each other around and wrestle, and when they're tired they'll lie down in the grass together.

    Jack is truly an inspiration. I've owned a lot of kittens in my life, but Jack is the happiest, most playful of them all. He doesn't feel sorry for himself. Heck, for all he knows, all cats are just like him. People who know Jack don't feel sorry for him. They cherish him for the treasure that he is. I have talked to a few people who haven't met him personally who tend to pity him, but they just don't understand. Jack doesn't need pity. I think Jean (who has Gumbo the eyeless ginger) said it best when she told me that cats don't have disabilities, they have adaptabilities.