Idle Work
无用功(idle work), 此释义来源于网络辞典。
goose chase
goose chase » 无用功 we were all very tired ,because we sat down under a tree and had a rest.
lipstick on a pig ; Flogging a dead horse
unnecessary amount of work
Reinvent the wheel
无用功又称额外功。机械克服额外阻力(如起重机提起重物时起重机臂的重力以及绳索和滑轮间的摩擦力)所做的功,同额外功为并非我们需要又不得不做的功。