He does everything on his own. 他自己做每件事

He will finish everything on his own. 他將會獨立完成每件事

He has been doing everything on his own.他自己做每件事（從過去到現在，有時間的延續性）

He has to complete everything on his own. 他必須自己完成每件事

He need to complete everything on his own. 他需要自己完成每件事

He intends to do everything on his own. 他想自己做每件事

沒有in one"s own.這種搭配

只有on one"s own

Success in study mainly depends on one"s own efforts.

學習主要靠自己努力。