4 还有翻译3句话，非常感谢
1 Historically,the primary source of lead emissions has been the result of tetraethyl lead additives to gasoline.
2 Legislative controls have done much to lessen the impact of this source in the United States.
3 Stationary sources include mining,smelting,waste incineration,iron and steel production,lead alky manufacturing,and battery manufacturing,where the lead is released by stack and fugitive emissions.
很是感谢
参考答案:1 从历史的角度讲，铅挥发的最初来源是添加到汽油中的四乙基铅。
2 在美国，法律的约束作用已经大大减少了这一来源的铅的影响。
3 固定污染源包括采矿、熔炼、垃圾焚烧、钢铁制造、含铅酒精制造以及电池生产，在这些行业中铅以成堆的方式或是无形的散射物被泄漏出来。