irrigation principle

例句：

1. 1.The farmer used to irrigate his fields with rainwater.
   农民过去用雨水灌溉他的田地。
2. 2. The irrigation system is designed to prevent soil erosion.
   灌溉系统旨在防止土壤侵蚀。
3. 3.The farmers have switched to using treated water for irrigation.
   农民们已经转向使用处理过的水进行灌溉。