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问题 选择题

关于机动运动和参考系，说法中不正确的是（  ）

A．平常说的运动和静止都是相对参考系而言的

B．所谓参考系就是我们假设为不动的物体，以它为标准来研究其他物体的运动

C．相对于不同的参考系来描述同一个物体的运动，其结果一定相同

D．研究航行的轮船内的每个人的运动，取轮船为参考系最为适宜

答案

答案：C

参考系的选取是任意的，选作参考系的物体就是假定不动的物体，所选择参考系不同，物体的运动描述也可能不同，C对；

听力题

Here’s the story about Ming’s life on the waters. Ming has lived all his life on a wide r    (1)  in China. His home is a large house-boat with a roof, one of hundreds that move up and down. In about six years he has not once been on l    (2) , but he is never lonely. He is a strong swimmer. In fact（实际上), he could swim before he could walk . When he wants to play with his f    (3) , he just swims across to their boats or asks them to v    (4)  him.

Ming’s father is a fisherman but he never u    (5)   a line or a net（网）. Great black birds called cormorants（鸬鹚）do the fishing for him. Rings （圈） have been put around the birds’ n    (6)  so that they cannot eat the fish they catch. They have been taught to b    (7)  the fish to people. And then people reward （奖励） them with a fine big fish as soon as their work is f    (8)  . Ming loves watching the cormorants, but better still he likes going s    (9)  with his mother. The shops, of course, are boats very like his o    (10) .
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问答题 简答题

什么是强制戒毒？
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