句子分析：Usually when I come home from school.

句子分析：Usually when I come home from school.
句中home是副词、from school是介词短语都是修辞动词come的,可句中usually和when怎样去理解,它们是什么成分、位置为何在前?
完整的句子是;I exercise every day,usually when I come home from scool.