gōng / chéng / shī / gēn / jù / shè / bèi / de / fú / ān / shù / xuǎn / zé / le / hé / shì / de / diàn / yuán工程师根据设备的伏安数选择了合适的电源。The engineer chose a suitable power supply based on the equipment's volt-ampere rating.