标签：话题作文 话题 英语四级作文
字数：1000字
提要：Air pollutionAir pollution comes from factories, power stations and cars. Chemicals in the smoke from power stations cause a lot of damage. They can travel hundreds of miles in the wind before falling to the ground in the rain. But this "chemical rain" gradually destroys trees in the forests and kills fish in the lakes. In Germany, over 50% of the country＇s trees had been damaged by the..