why引导的主语从句why he didn't come is that he was ill. 对吗?

why引导的主语从句
why he didn't come is that he was ill. 对吗?

对的,他没来的原因是他病了.
也可以这样表达:The reason why he didn't come is that he was ill.
The reason for his absence is that he was ill.