新概念入门第四册 38 PART B
[audio]http://sound.yywz123.com/tingbbs/xgnrm/xgnrmdsic/38b.mp3[/audio]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. Drinks can be cooled by placing them on ice rather than adding ice to them. (1)_______________________. Ethanol is more effective at a concentration of 50-70 percent; below 20 per cent, its bactericidal action is negligible. Spirits labeled 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. (2)_______________________. Those planning a trip to remote areas, or intending to live in countries where drinking is not readily available, should know about the various possible methods for making water safe.
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