or和either的用法區別

Do you want one or two?

你要一個還是兩個？

The operation could prolong his life by two or three years.

這次手術可使他多活兩三年。

Well, I think she's either Russian or Polish.

嗯，我看她不是俄羅斯人就是波蘭人。

There is a large window on either side of the front door.

前門兩側各有一個大窗戶。