农田土壤的主要污染物及其污染途径有哪些？
参考答案：我国农田土壤的主要污染物有汞、镉、铅、铬、砷等重金属污染物，有机磷、有机氯等有机污染物，还有残留的农膜。农田土壤的污染途径包括农药、化肥和农膜的不正确使用；生活和工业污（废）水灌溉；矿业、工业固体废弃物在农田的不合理堆放与处置；工业生产、汽车尾气排放及汽车轮胎磨损产生的大量含重金属的有害气体和粉尘在农田的自然沉降。
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| Many Chinese middle school students dream of becoming great 1 . How wonderful it is to be a hero, liked by a lot of people, 2 Yang Liwei and Jackie Chen! However, this is the reason 3 they feel bad: they think they are not brave enough to do the things they like or to 4 their teacher's questions because they're afraid that people will laugh at them. It's very natural for young people 5 , especially in China. When I was a 6 I was also terribly shy. When I was among strangers, I could 7 breath! But after making some efforts I became as brave as my friends. I started to 8 for the school magazine and joined a sports team. Writing helped me grow and become mature (成熟的), and the friends I 9 on the sports team became my best friends. We played basketball, watched movies, and went swimming on hot summer days. A few years 10 when I went to college in New York City, I felt self-confident, like a hero! | ||||
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