But they spent a lot of time, energy, and money on being sure that they would have a supply of water to hold them for a long siege.

他们花费了大量的时间,精力,和金钱来确保,在长期的围城中他们可以获得足够的水源

耶鲁公开课 - 古希腊历史简介课程节选

Separating our water supply from sewage and learning how to do wastewater treatment was a really important part of reducing infectious diseases.

把净水和污水分开,以及学会污水处理的方法,是减少感染性疾病传播方法中的重要部分

耶鲁公开课 - 生物医学工程探索课程节选