draw on butter or carve ice—a futile undertaking;work fruitlessly; work hard but to no avail ? 你難道不覺得自己在～嗎？有什么用呢？ Don’t you think that you’re drawing on butter or carving ice? What’s the use of it?
畫脂鏤冰hua zhi lou bing
draw on butter or carve ice—futile undertaking
畫脂鏤冰huà zhī lòu bīnɡ
鏤：雕刻。在油脂上畫畫，在冰上雕刻。比喻做無用功，白費(fèi)力氣。a futile undertaking, work hard but avail, work fruitlessly