a house of cards
    不可靠的計(jì)劃、空中樓閣
    例句：
    I'm afraid you've been building a house of cards; no one is going to help you in a scheme like that.
    恐怕你一直在考慮的計(jì)劃是不可靠的空中樓閣，沒(méi)人會(huì)幫助你去搞那樣的一個(gè)計(jì)劃。