1.themselves是复数第三人称反身代词,在句中多用作宾语,有时也可用在主语或宾语之后充当同位语,此时多表示强调,作主语的同位语时还可置于句尾。themselves偶尔也可用作主语和表语。
2.themselves有时与某些动词(短语)搭配可指“身心处于正常状态”。

by themselves
全靠他们自己alone; without help
They did it all by themselves.他们全靠自己完成这事。

in themselves
本身,自身without considering the rest
They are not bad in themselves but they're so weak-minded.他们本质并不坏,只是优柔寡断。

They washed themselves in the river.他们在河里洗澡。
You had better ask the students themselves.你最好问问那些学生本人。
They themselves have often made that mistake.他们自己也常犯那种错误。
They decided to go there themselves.他们决定亲自到那里去。
Who suffer by their whims?Themselves always.为他们的狂想吃苦头的是谁呢?总是他们自己。
Those poor children were themselves.那些可怜的孩子就是他们。
They soon came to themselves.他们很快就苏醒过来了。