ReadWriteQuiz
Chinese dictionary
n.derogcastle of cards―plans or hopes that are unlikely to be realized; mirage
这是脱离群众的空中楼阁。
It is an unrealistic plan that is divorced from ordinary people.
他们的计划完全是空中楼阁。
Their plan is built on sand.
不要想些空中楼阁的事了。
Don't think of castles in the air.