多年的习惯已经让他的偏见根深蒂固。

Years of habit have ___entrenched his prejudice deeply.

军队决定在阵地周围挖战壕以巩固防御。

The army decided to ___entrench their position by digging trenches around it.

坏习惯一旦养成，就很难改变。

Bad habits can become deeply ___entrenched once they are formed.