新概念第四册 Lesson 38 Water and the traveller

　　Ice is only as safe as the water from which it is made, and should not be put in drinks unless it is known to be safe. Drink can be cooled by placing them on ice rather than adding ice to them.

　　Alcohol may be a medical disinfectant, but should not be relied upon to sterilize water. Ethanol is more effective at a concentration of 50-70 per cent; below 20 per cent, its bactericidal action is negligible. Spirits labelled 95 proof contain only about 47 per cent alcohol. Beware of methylated alcohol, which is very poisonous, and should never be added to drinking water.

　　If no other safe water supply can be obtained, tap water that is too hot to touch can be left to cool and is generally safe to drink. Those planning a trip to remote areas, or intending to live in countries where drinking water is not readily available, should know about the various possible methods for making water safe.

　　RICHARD DAWOOD Travellers' Health

　　New words and expressions 生词和短语

　　contamination

　　n. 污染

　　sanitation

　　n. 卫生，卫生设备

　　sewage

　　n. 污水

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