无用功

无用功
wúyònggōng
名
1 useless effort:
- 他忙了半天，尽是无用功。 He was busy all day and achieved nothing.
2 【物】 useless work

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无用功
wúyònggōng
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。 {unavailable work; work done by a machine to overcome extra resistance (such as the gravity of the arm of a crane and the friction between the rope and the pulley in lifting heavy goods)}�