扫描二维码，直接登录
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
还没有题目讲解（毕出老师会陆续发布对官方考题的解读，请保持关注）。
（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
登录 或 注册 后可以参加讨论