【文章內(nèi)容簡介】
heir total are encouraged to use bicycles, which are thought to help keep the air clean.but this change does not e easily. a large number of workers may find themselves without jobs if a car factory cioses down. thus the problem of air pollution would bee less important than that of unemployment. although cars have led us to a better life, they have also brought us new problems.每年有越來越多的汽車在新車的人數(shù)以百萬計(jì)的生產(chǎn)道路。出六個(gè)一工程美國人制造汽車,駕駛卡車,修建道路或填補(bǔ)氣體。美國人不能沒有車!大多數(shù)美國人將很難想象沒有汽車的生活。然而,一些已經(jīng)認(rèn)識到空氣污染嚴(yán)重的問題,汽車造成的。污濁的空氣變成有毒的和危險(xiǎn)的健康。一個(gè)辦法讓污濁的空氣,就是自己做,無污染的汽車。但要建設(shè)一個(gè)清潔汽車談何容易。在這一領(lǐng)域的進(jìn)展非常緩慢。