用细线拴住一端粗、一端细的实心胡萝卜并悬挂起来，静止后胡萝卜的轴线水平，如图甲所示；在拴线处沿竖直方向将胡萝卜切成A、B两段．A、B哪段重些呢？甲、乙、丙三个同学提出各自的猜想：
甲：A较重 乙：B较重 丙： A、B一样重．
（1）请设计一个简易实验，判断A、B的轻重．
所用器材：
操作方法：
现象及结论：
可用天平测量A、B两段萝卜的质量进行比较；
所用器材：①天平．
②操作方法：分别把A、B放入调好的天平两盘，观察指针的位置；
③指针偏向哪侧，则哪侧重
Protecting (保护) wild animals is our duty. Because wild animals are important to us. They live with us on the earth together. If there are no animals on the earth, we will not live on, 46 . So we should take good care 47 them to help us live a healthy life. 48 some people still don’t realize the 49 of protecting wild animals. They often kill wild animals for food or for money. Every day there are many wild animals being 50 . So lots of wild animals have died out (灭绝). We can’t see them any more. Today the number of wild animals 51 becoming smaller and smaller. If we don’t protect them, they will all die out. If this goes on, there will be no animals left on the earth. 52 , more and more people have begun to do many things to help protect wild animals. They ask people 53 killing wild animals. They get people to know that protecting wild animals is one of the most important things. Now many countries have made 54 laws (法律) to protect wild animals. Now that (既然) wild animals are so important to man, we should do our 55 to protect them and it means human beings can make friends with animals and get on well with them.
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