下表列出了实验测定的几种物质的密度．
几种物质的密度（常温常压下，单位：kg/m3．）
| 铜 | 8.9×103 | 水银 | 13.6×103 | 氧气 | 1.43 |
| 铁 | 7.9×103 | 纯水 | 1.0×103 | 空气 | 1.29 |
| 铝 | 2.7×103 | 煤油 | 0.8×103 | 水蒸气 | 0.60 |
| 冰 | 0.9×103 | 酒精 | 0.8×103 | 氢气 | 0.09 |
密度是物质的一种特性，在通常情况下，每种物质都有一定的密度，不同物质的密度一般是不同的，对于同一种物质来说，其密度与该物质的形状、质量、体积、位置和运动状态无关．
从表中可看出不同物质的密度一般不同，每种物质都有确定的密度．
故答案为：同一种物质不同状态下的密度不同；一般不同物质的密度不同（有特殊）；一般固体的密度大于液体的密度（有特殊）．
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| There are many kinds of pollution around us, 1 air pollution, soil pollution, noise pollution and light pollution. They are bad 2 our health in many ways. Burning gas, oil and coal creates air pollution. It can cause sore eyes and 3 problems. With the increase of pollution and the development of industry, litter is everywhere. It makes our environment dirty. People put lots of rubbish in the land. Farmers use too many 4 in the fields. They destroy the soil. So soil pollution has become serious. Noise pollution can make people 5 . For example, people may lose their hearing if they work in a 6 place for a long time. Too much noise can cause high blood pressure 7 . Working for a long time in strong, changeable light 8 cause some kinds of illnesses. It makes people feel 9 and is especially bad for the eyes. With 10 pollution, our planet will become greener and our health will be better. Let's be greener people. | ||||
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