问题
填空题
同学在用托盘天平称量时，将药品与砝码的位置放颠倒了，平衡时称得药品质量为5.7g，则样品的实际质量为 ______．
答案
由左盘的质量=右盘的质量+游码的质量可知：砝码质量=物体质量+游码的质量，所以物体质量=砝码质量-游码质量，即：物体质量=5.0g-0.7g=4.3g．
故答案为：4.3g
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同学在用托盘天平称量时，将药品与砝码的位置放颠倒了，平衡时称得药品质量为5.7g，则样品的实际质量为 ______．
由左盘的质量=右盘的质量+游码的质量可知：砝码质量=物体质量+游码的质量，所以物体质量=砝码质量-游码质量，即：物体质量=5.0g-0.7g=4.3g．
故答案为：4.3g
We live on the earth. We use the sea around us. What do we take from the ocean? And what do we give to it? We take fishes from the ocean—millions of kilograms of fish, every year, to feed millions of people. 小题1: We take minerals(矿物) from the ocean. We can get salt by evaporating(蒸发) seawater. 小题2: Many other minerals, such as gold, can be also got from the sea, but not by simple evaporation.小题3: Seaweed(海草) becomes food of many kinds— even candy, and ice cream—as well as medicine. Believe it or not, fresh water is another gift from the sea. We can’t drink ocean water. 小题4: But ocean water becomes fresh water when the salts are removed. In the future, we will find ourselves depending more and more on fresh water from the sea. The sea gives us food, fertilizer, minerals, water and other gifts. What do we give the sea? We pollute the ocean all the time. 小题5: Throwing waste into the ocean is killing off sea life. Yet as the world population grows, we may need the sea and its gifts more than ever. We are finally learning that if we destroy our sea, we might also destroy ourselves. Hopefully, it is not too late. 根据以上内容，从下 * * 个选项中选择适当的句子还原到短文中，使短文完整与正确。将其标号在答题卡上涂黑。（每小题2分，共10分）
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