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题库 / OG2015-SC-88
Often visible as smog, ozone is formed in the atmosphere from hydrocarbons and nitrogen oxides, two major pollutants emitted by automobiles, react with sunlight.
ozone is formed in the atmosphere from
ozone is formed in the atmosphere when
ozone is formed in the atmosphere, and when
ozone, formed in the atmosphere when
ozone, formed in the atmosphere from
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（Often visible as smog,） ozone is formed in the atmosphere from hydrocarbons and nitrogen oxides, （two major pollutants emitted by automobiles）, react with sunlight
A from介词后面不能跟句子，只能+名词
and when 不平行
BCD是fragment， hydrocarbons and nitrogen oxides react with sunlight是一个完整的句子，描述ozone形成的时间。
答案是B 哦
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