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◎勞而無(wú)功láo’érwúgōng
[bay the moon;work hard but to no avail;accomplish little; fool's errand; milk the bull; preach to the winds wash a blackamor white] 費了力氣但沒(méi)收到成效
與不可，強不能，告不知，謂之勞而無(wú)功?！?span id="vbxxhxln" class="bold">《管子·形勢》
(好工具)