Acid Rain 酸雨What is true of Acid Rain?About pollution

Acid Rain 酸雨
What is true of Acid Rain?
About pollution

你说的True 具体指什么呢 是酸雨的定义还是形成?
定义：Acid rain means the rain that below pH value 5.6 .
形成：Acid rain is mainly causes by sulphur dioxide and nitrogen oxide.
These kinds of gases are produced by factories and vehicles.
不知道合不合适,希望能帮你哈 xd