Iraq was Iran's mortal enemy.

伊拉克曾是伊朗的死敌。

You really have a mortal enemy.

你还真有一个死敌。

Hurons, this is your mortal enemy.

休伦人，他就是你们不共戴天的仇人。

But, English does have one possible mortal enemy-itself.

但是，英语的确有一个可能的致命敌人这就是它自身。

Never think of Satan as anything less than your mortal enemy.

千万不要以为撒但的能力低于世上的敌人。