be at work idiom
在工作
to be working
The labourers were at work in the fields. 劳动者们正在田间劳动。
literary起作用，有效（尤指明显的或不良效果）
to be having an effect, usually an obvious or bad effect
It seems as though forces of destruction are increasingly at work throughout society. 破坏力量似乎正在给整个社会造成越来越坏的影响。