1. by oneself 独自；独立；自动.如：
She did it all by herself. 这是她独立做的.
The machine runs by itself. 这机器自动运转.
2. of oneself 自发地,自动地.如：
The enemy will not perish of itself. 敌人不会自行消灭.
3. to oneself 独自享用.如：
I want a bedroom to myself. 我想一个人要一间卧室.
4. for oneself 为自己
She kept the largest apple for herself.
她把最大的苹果留给自己.
oneself只与by,of,to,for连用,没有with oneself,明白吗?