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问题 填空题

如图所示，两小球悬挂在天花板上，a、b两小球用细线连接，上面是一根轻质弹簧，a、b两球的质量分别为m和2m，在细线烧断瞬间，a球的加速度为________，b球的加速度为________。（取向下为正方向，重力加速度为g）

答案

-2g；g

居住在墨西哥的印第安人培育出玉米，墨西哥因此有“玉米故乡”之称，他们也将自己称为“玉米人”。今天我们能吃到金黄的玉米得益于（   ）

A．达·伽马的印度洋之行

B．郑和下西洋

C．哥伦布横渡大西洋之行

D．麦哲伦的环球航行
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单项选择题

In the New York street a small truck hit a big tree. The truck was full of glasses and they were all (41) now. The driver came out of the truck and looked at the broken glasses. He was very (42) . And people in the street were (43) for him.
Then an old man walked to the driver, looked at him for a few (44) and said, "My poor boy, I think you must (45) a lot for it."
"Yes, "was the bad answer.
"Well, "said the old man," hold out your (46) . Here’s some money for you, and I hope all the people around here will give you (47) ,too. "With these words, he walked away.
The driver held out his hat and over a hundred people came and put their money in it. At last the driver (48) a bag and put all the (49) in. Then he looked at the people and said, "Thank you very much. I’m working for that old man and all these (50) are made in his factory. \

[A] hats [B] trucks [C] glasses
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