阅读理解:
Heavy metals are persistent; they do not break down to other chemicals in the strially polluted sites usually undergo intensive clean-up and rehabilitation because heavy metals are a health concern once they enter the food trace metals are alleged to cause cancer and are also known to cause poisoning.
The main idea of this paragraph is__________.
Nature of Heavy Metals
B.Potential Hazards of Human Contaminated Soils
y Metals and Food Chain
arch on Channels of Heavy Metals Getting into Human Food Chain
正确答案:B
答案解析:本段文字讲的是:受到工业污染的土壤含有重金属,而重金属很稳定不容易降解,其中的'某些微量重金属能使人致癌或中毒。可以看出其中心内容是:受污染土地的潜在危险,选择B。