理工類英語考試練習小題

　　閱讀理解：

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

　　正確答案：B

答案解析：本段文字講的是：受到工業污染的土壤含有重金屬，而重金屬很穩定不容易降解，其中的'某些微量重金屬能使人致癌或中毒。可以看出其中心內容是：受污染土地的潛在危險，選擇B。