| 1. | Systemic insecticides have shown particular promise . 内吸杀虫剂看来特别有效。 |
| 2. | Both aldrin and chlordane are valuable insecticides . 艾氏剂和氯丹都是重要的杀虫剂。 |
| 3. | Resistance to insecticides has been apparent for many decades . 杀虫剂抗药性的出现已有数十年。 |
| 4. | Farm workers frequently come in contact with these insecticides . 农场工人常常接触这些杀虫剂。 |
| 5. | Insecticides are widely used for controlling most insect pests . 杀虫剂广泛应用于防治大多数害虫。 |
| 6. | Spraying the area around buildings with an insecticide also prevents insect buildup . 建筑物周围喷洒杀虫药也能防止昆虫孳生。 |
| 7. | Spraying the area around buildings with an insecticide also prevents insect build up . 建筑物周围洒布杀虫药也能防止昆虫孳生。 |
| 8. | As preventive, spray plants with systemic insecticide or fumigate them regularly . 作为预防措施,要用内吸杀虫剂对植物定期喷洒,或熏蒸。 |
| 9. | I have decided to specialize in plant chemicals that can be used for insecticides . 我已经下决心专门研究可以用作杀虫剂的植物中的化学物质。 |
| 10. | Spraying with insecticides and fungicides may be necessary to control any insects and diseases . 也许有必要喷洒杀虫剂和杀菌剂以防止病虫害。 |