2010年职称英语完形填空 讨论专帖？ Passage 13 Land pollution involves many kinds of wastes. For many years, all wastes were dumped into sanitary landfills. Sanitary landfills are large pits where garbage is buried under layers of dirt. When hazardous wastes are put in these landfills, toxic substances can seep into the groundwater and enter the food chain. Hazardous wastes are those kinds of wastes that are destructive or dangerous to the environment. They can be poisonous corrosive, flammable, explosive, or radioactive. They can pollute the air or cause fires or explosions. These wastes can also cause health problems for humans and animals. For these reasons, it is important to dispose of hazardous wastes in secured landfills where they cannot leak. A secured landfill is located on clay ground, and the pits are lined with plastic and nylon sheets to keep the hazardous wastes in the pit. One kind of hazardous wastes, radioactive waste, leads a special disposal probelm. Radioactive waste is created by industries and nuclear power plants that use radioactive materials. Radioactive materials give off energy as their atoms change. This energy is invisible, but very powerful. It can harm living tissues in plants and animals. Radioactive waste can remain hazardous for over 100 years. They must be stored in containers that can hold them without leakage for at least that amount of time. 查看更多0个回答 . 5人已关注
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