alachlor

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 use this herbicide to control the growth of weeds in their crops.
   农民们使用这种除草剂来控制他们作物中杂草的生长。
3. 3. Due to its effectiveness, alachlor is often used as a pre-emergence herbicide.
   由于其高效性，莠灭净常被用作苗前除草剂。