First, the weapons should be intended for use only in retaliation after a nuclear attack. Second, the possession of the weapons must be a temporary expedient.
首先，这些武器应当只在遭受核袭击后反击时才使用。其次，这些武器的拥有必须是一种临时的应急手段。
《柯林斯英汉双解大词典》
2
The curfew regulation is a temporary expedient made necessary by a sudden emergency.
宵禁令是应对突发事件时必要的临时权宜之举。
《柯林斯英汉双解大词典》
3
The disease was controlled by the simple expedient of not allowing anyone to leave the city.