if he had only known he was building his own house,he would have done it all so differently.

题目

if he had only known he was building his own house,he would have done it all so differently.
要按照语法的,字字翻译,

答案

这是一句虚拟语气的句子表示假设的情况和过去发生的事实相反.也就是说“他不知道他建的是他自己的房子,所以建得不怎么样”.原句意思：
“如果当时他知道在建的是他自己的房子,他会把它建得与现在完全不同”