lives were being saved in emergrncies.为什么用were being saved 而不是were saved

其实两种说法，在语法上都对。这主要看在什么语境下用。
Lives were being saved in emergencies.强调“现场感、真实感”，予人“身临其境”的感觉。
Lives were saved in emergencies.则是“平铺直叙”，只是“记录事实”。
在许多文学作品中，这两种被动式都经常用，表达的情绪各异。

这是被动语态的过去进行时态.
were saved 是被动语态的过去式,无疑问
要表达进行时,就在be 后面加 being
例如
The cat is being taken care of 那只猫正在被照顾