题干

据报道,美国计划从2021年开始每年送15 000名旅客上太空旅行。如图所示,当旅客围绕地球沿椭圆轨道运行时, A、B为运动的近日点和远日点,则 (     )

A:在A点的角速度大于B点的角速度

B:在A点的加速度小于B点的加速度

C:由A运动到B过程中动能减小,势能增加

D:由A运动到B过程中引力做正功,机械能增大

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答案(点此获取答案解析)

A,C

同类题4

先读通下面的短文,然后从各题所给的A、B、C、D四个选项中,故答案选出最佳选项。

    It has been some time since(自从) Jack saw the old man. In fact, Jack moved away from the country and was busy 1his work. There, Jack had2 time to think about the past and often had no time to 3 with his wife and son. He was working for his future.

    One day, his mother 4him over the phone that Mr Belser, their neighbour had died and the funeral(葬礼) would be 5Wednesday.It took a long time 6 Jack gave an answer because he had not thought of Mr Belser for a long time. “Well, he didn't 7 you. Every time I saw him, he'd ask 8you were going. He'd 9the days you spent with him, ” Mum told him.

    It had been about two weeks since Mr Belser died. One day, Jack 10 a package(包裹). There, inside was a gold 11.The box was from Mr Belser. Jack's hands shook(晃动) as he read the note inside. “Upon my death(死亡) please give this box to Jack Bennett. It is the thing I value most( 珍视) in my life.” There inside he 12 a beautiful gold packet watch. He opened the cover. Inside he found these words, “Jack, thanks for your 13 !——Harold Belser.”Jack held the watch for a few 14, then called his office and canceled (取消) his meetings for the next two weeks. He needed some time to spend with his wife and son.

    No matter how( 无论怎么样) busy we are, we should always remember to spend some time with the person we love. They are 15part of our life.