1）adj.两者
一般单独修饰名词（复数）做前置定语（但名词前不能有其他限定词修饰）,不做表语/补足语.
如：There are many flowers on both sides of the street.
2）pron.两者
可以单独使用（相当于名词）,也可以构成“both of + 其他限定词 + 名词（复数）”或“both of + 代词”结构.
Both are my good friends.
Both of the boys over there are my good friends.
Both of them are my good friends.
3）adv.两者都
一般放在句中,即be动词之后/前均可,助动词/情态动词/行为动词之前.
They are both my classmates.
They both can play soccer well.
They both have a good son.
4）conj.不仅...而且...；...和...都...
一般构成both...and...结构,用于连接句中任意两个并列部分.
如果并列两个主语,谓语动词一般采用复数形式.
如：Both you and I are students.
I can speak both English and Chinese.
They can both sing and dance.
The boy is so lazy that he sleeps both in the daytime and at night.
