We both tried to get the coins.

We both tried to get the coins.
They are both students.
Both of them are students.
第一句中的both是同位语
第二句中的both也是同位语
both用在助动词,BE动词,情态动词之后,行为动词（实义动词）之前.
第三句中的both是代词作主语.
Both books are interesting.
本句中的BOTH作定语,是形容词.