Both可作形容词、代词或副词用,意思是“两个”、“双方”、“两个都”.在句中可作主语、宾语或同位语.
如：Both are right.两者都对.(主语)
I like both.两个我都喜欢.(宾语)
Both可参与构成名词词组,也可和动词连用,还可与and构成并列连词.
Both与动词连用时,大多数放在系动词be之后,其它动词之前.
如：His parents are both workers.
They both enjoy reading.
若句中谓语动词包含情态动词或助动词时,both大多放在第一个情态动词或助动词之后.
如：The bridges must both be built this year.
两座桥都必须在今年修建.
kate and Mary have both gone to English.
凯特和玛丽都去了英国.
Both可与and构成并列连词,连接两个性质相同并在句中作相同成分的并行结构.
如：Both he and his brother are good at English. (连接两个主语)
She can both dance and sing.(连接两个谓语动词)
Mary is both kind and beautiful.(连接两个表语)
