DDT was once used as a pesticide to permanently obliterate all insects. Now, DDT has become ineffective and is no longer used as a pesticide. Why were the populations of insects able to survive applications of DDT?
举一反三
- After the debate, the European Parliament will （） A: consider DDT’s positive uses B: continue to keep DDT illegal C: remove some restrictions on DDT use D: study DDT’s impact on human health
- DDT属于（）。
- 关于有机氯农药DDT和林丹，下列叙述不正确的是（） A: 林丹比DDT更易溶于水； B: DDT比林丹的挥发性强； C: DDT比林丹对生物的毒性更强； D: DDT比林丹的生物降解性差。
- What decision was made by the US government in 1969? A: )The use of DDT must stop right away. B: ) The use of DDT must stop before 1971. C: ) The use of DDT should be encouraged.
- DDT又被称为（）。