68. Often vision as smog, ozone is formed in the atmosphere from hydrocarbons and nitrogen oxides, two major pollutants emitted by automobiles, react with sunight.
(A) ozone is formed in the atmosphere from
(B) ozone is formed in the atmosphere when
(C) ozone is formed in the atmosphere, and when
(D) ozone, formed in the atmosphere when
(E) ozone, formed in the atmosphere from
In choice A, the construction from hydrocarbons and nitrogen oxides..react is ungrammatical.
我不太清楚这个句子的结构,为什么A的表达不合语法呢? 谢谢了. | 
