I dont know the reason why he was late 为什么不用that

I dont know the reason why he was late 为什么不用that I dont know why he was late.这个句子里为什么用why不用that? I dont know why he was late for school again. THE REASON WHY HE WAS LATE WAS THAT HE MISSED HIS TRAIN.为什么要 the reason why he was late was that he got up late the house the reason that he was late was unknow 对么 为什么 The reason why he was late was that he was held up in the tr The reason why he was so late was that he missed the first b The reason why he was late was (that) he missed his train 我想 句子成分分析The reason why he was late was that he had taken a wro I dont know why he was late for school again.（同义句转换） The reason why he missed the bus was that he got up late.