air castle

Then Ibrahim looked once more in the surface of the diamond and saw a great web like that of a spider hanging in the air round the castle.

易卜拉欣又看了一次钻石面，这回看见一张蜘蛛网似的大网悬在空中，罩着城堡。

Short of perfect Regional Innovation System, National Innovation System will be nothing else but air castle.

没有健全的区域创新体系，国家创新体系无异于空中楼阁。

But your last quotation still seemed like air castle which made me failed to reach for.

只是你们上次的报价还是象空中楼阁一样让我可望而不可及.

Because of the disjoint of the theoretical and practical research of reading instruction, many theories can not be put into practice for proof-test finally. So the theory becomes an air castle without any practical applicable worth;

关于阅读教学对话的理论研究与实践研究脱节，很多理论最终难以付诸实践和接受实践的检验，理论建构成为空中楼阁，缺乏实际应用价值；