In an average winter, highway
departments spread some ten million tons of salt to keep roads safe. The
corrosive effects are well known, but for years they’ re been dismissed with the
argument that at around $ 25 a ton, salt is far cheaper than any
alternative. Lately, economists have added up the actual costs.
The Environmental Protection Agency estimates that salt-induced road damage and
vehicle corrosion cost $ 3 billion a year. That does not include damage to
underground cables, which adds hundreds of millions to utility bills. Nor does
it reflect the cost of brine leaking into porous water pipes, threatening the
water supply. Salty water leaches into roadbeds, kills evergreens and poisons
streams. The various costs probably add another $ 2 billion A. road damage B. vehicle corrosion C. damage of underground cables D. car accident
[单项选择]Thursday, the terrible noise was {{U}}substituted{{/U}} by the grim, steady hum of search and recovery. A. replaced B. expired C. returned D. restored
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