when they cannot operate efficiently equipment much more adv

when they cannot operate efficiently equipment much more advanced than the devices they used back i
when they cannot operate efficiently equipment much more advanced than the devices they used back in the country school or hospital.这句话意识明白.第一个不明白是在much more advanced 后面是不是省略了device.另外used back 怎么翻译好
they will feel intense occupational stress when they cannot operate efficiently
equipment much more advanced than the devices they used back in the country school or hospital. 翻译：他们将感觉强大的职业压力，当他们不能有效的操作非常先进的设备比他们在农村学校使用过的设备