要加逗号，就想too一样，放在句末，用逗号隔开，都表示“也”的意思，只是too用在肯定句，either用于否定句。
Well, I think she\'s either Russian or Polish.
嗯，我看她不是俄罗斯人就是波兰人。
There is a large window on either side of the front door.
前门两侧各有一个大窗户。
You can park on either side of the street.
这条街两边都可停车。
水利万物而不争,
而万物莫能与之争。
