1
as stubborn as a mule
固定明喻，形容人非常固执。
He is as stubborn as a mule and never changes his mind.
他像骡子一样固执，从不肯改变主意。
骡
mules — plural of mule
先理解核心含义，再看它在真实句子里的用法。
骡
hybrid offspring of a male donkey and a female horse; usually sterile
He is as stubborn as a mule and never changes his mind.
他像骡子一样固执，从不肯改变主意。
The generally sterile male or female hybrid offspring of a male donkey and a female horse.
一种前部覆盖脚面、后部无鞋帮或鞋带、露出脚跟的鞋
Any shoe with an upper covering the front of the foot but without a back flap or strap, leaving the heel exposed.
公驴与母马所生的杂交后代；通常不育
hybrid offspring of a male donkey and a female horse; usually sterile
The generally sterile hybrid offspring of any two species of animals.
The farmer used a mule to carry heavy sacks up the mountain path.
农夫用一头骡子把沉重的麻袋驮上山间小路。
Mules are known for being stronger and more patient than horses.
骡子以比马更强壮、更有耐心而闻名。
She watched the mule pull a plow across the field.
她看着骡子拖着犁穿过田地。
固定明喻，形容人非常固执。
He is as stubborn as a mule and never changes his mind.
他像骡子一样固执，从不肯改变主意。
用‘a mule’指代倔强的人，为比喻用法。
If you refuse to listen to others, you are being a mule.
如果你拒绝听别人的意见，那你就是在犯犟。
Not this
There are many mule on the farm.
Use this
There are many mules on the farm.
mule 是可数名词，复数形式为 mules；汉语“许多骡子”没有复数标记，但英语中复数概念必须用复数形式。
Not this
He is as stubborn as mule.
Use this
He is as stubborn as a mule.
在 as...as... 比较结构中，mule 是单数可数名词，前面需要不定冠词 a；汉语“像骡子一样犟”没有冠词，容易漏掉。