他迟到的理由是他起床晚了。
用英语表达
翻译如下：
The reason why he was late was that he got up late.
重点词汇释义：
迟到 be late;?come late;?arrive late;?be late for;?kiss the hare's foot
理由 reason;?excuse;?justification;?account;?regard
起床 rise;?get up;?get out of bed;?astir;?be up