同位语从句当中it is not surprising that...和it is notsurprising why...的不同之处？
如下语境，这两个表达是否都可以？
He was stuck in traffic jamsthis morning. It was not surprising that/ why he was late for class.
第一这个从句不是同位语从句，而是外置主语从句，it为形式主语。用why为非正式语体。词典对why的解释之一就是that，非正式使用方法。