sym-triazine

例句：

1. 1. This herbicide is effective against weeds in the field.
   这种除草剂在田间对杂草有效。
2. 2.The farmers used it to control the weeds in their crops.
   农民们用它来控制作物中的杂草。
3. 3.The chemical was banned in many countries due to its toxic effects.
   由于其毒性，这种化学物质在许多国家被禁止使用。