a lifelong [mortal, sworn] enemy 不共戴天之敌,死敌
enemy property 敌对国之资产
The enemy was driven back. 敌人(军队)被击退了
The enemy are in great force. 敌军大批出动
make many enemies 树敌过多
make enemy of... 与…为敌
an enemy of freedom 自由的敌人
an enemy to faith 信仰之敌
be one's own worst enemy=be nobody's enemy but one's own 自己害自己,自作自受
Every man is his worst enemy. 【谚】 最大之敌是自己[最困难的事莫过于战胜自我]
Never tell your enemy that your foot aches. 【谚】不要让敌人知道你的弱点.