开沟于

例句：

1. 1. The farmer had to dig a ditch for the irrigation system.
   农民必须挖一条沟来灌溉系统。
2. 2. The road was too narrow, so they had to dig a trench to accommodate the traffic.
   道路太窄了，所以他们不得不挖一条沟以容纳交通。
3. 3. The workers were asked to dig a deep hole for the new well.
   工人们被要求挖一个深洞为新井。