无米之炊（無米之炊）　

◎ 无米之炊 wúmǐzhīchuī

[a meal without rice—impossible for lacking the most essentials;make bricks without straw] 炊:做饭。古谚有“巧妇难为无米之炊”。比喻缺少必要条件[因而办不成]的事