帮我分析一下这句话的成分

before引导的是时间状语从句，
the little boy had run around the corner of the street and disappeared,是主句，用了过去完成时。
leaving the poor grandpa there alone to say sorry and explain to the angry owner of the house why he had rung the bell.是结果状语。

why引导的是宾语从句，做的是explain的宾语，因为这个宾语太长，所以后置了。
explain sth to sb，向某人解释某事。