听英语老师讲：My mother said,"you should do it by yourself".又有听到He did it himself.反身代词前l到底加不加by?

题目

听英语老师讲：My mother said,"you should do it by yourself".又有听到He did it himself.反身代词前l到底加不加by?

答案

My mother said,"you should do it by yourself.
My mother said,"you should do it by yourself
by oneself表示完全依靠某人自己,而没有依赖别人,相当于alone,在句子中作方式状语.
He did it himself
himself作主语同位语,表示他亲自做这件事.