the equipment used to keep a person alive when they are very ill, or injured

He's been on a life-support system since the crash. 自从发生车祸后，他就一直依赖生命维持系统。

the natural structures and systems that are necessary for living things, especially humans, to be able to live

The lack of rain is threatening all the region's life-support systems (= the earth, trees and rivers). 降雨稀少正威胁着该地区的整个生态环境。