1.by+反身代词表示a.没人帮助，自己单干b.没人作伴

The girls made the paper flowers all by themselves.这些纸花全是女孩们自己做的。
Last Sunday Jason’s parents went out and they left him by himself.上周日杰森的父母出去了，留下他独自一人。

2. for+反身代词表示a.为、替、给某人自己b.靠自己的努力

She asked for a ticket for herself.她为她自己买了一张票。
You must do it for yourself.你必须自己做。

3. of+反身代词表示自动地

The door opened of itself.门自己开了。

4. in+反身代词表示本身、本质

This isn’t a bad idea in itself.这主意本身不错。

5. to oneself表示专用

Ann had the room all to herself.这间房归安专用。

6. beside oneself表示发狂、忘形

He was beside himself with joy.他欣喜若狂。