explain 谓语,sth宾语,to sb.向某人
其实这就是个词组,固定搭配,不要老想着什么成分,意思是：向某人解释某种东西
eg;The general explained the present situation to his soldiers.将军向士兵解释当前的形势.
类似的词组有：play a joke on sb.take sth with sb.
explain to sb sth 其实也是可以的 eg; I explain to Mary about the reason i late . 我向Mary解释关于我迟到的原因..