空中楼阁 (kōng zhōng lóu gé)
A rich man asked an architect to build a three-story house for him. When the first story was finished, the rich man said to the architect: “I want only the third story; not the first and second stories.” The architect asked, “But without the first and second stories, how can I build the third story?” Shaking his head, he packed up his things, and left. This idiom indicates an unrealistic or impractical plan or theory.
从前有个富翁，愚蠢无知。他叫木匠给他造一座三层楼。于是木匠便开始量地基，叠砖，造楼。富翁看见木匠叠砖，心生疑惑，不晓得是怎么一回事，就问木匠：“你这是打算造什么？”木匠回答道：“造三层的楼呀！”富翁又说：“我不要下面二层，你先给我造最上一层。” 木匠答道：“没这样的事！哪有不造最下一层楼而造第二层楼的？不造第二层楼又怎么谈得上造第三层楼呢?“ 木匠无奈，摇头离去。