both与two的用法区别
强调两个人和物时，不止是一个，才可用both,
如：There were two dogs on the porch. Both were fast asleep.
门廊上有两只狗，都在熟睡。（不止是一条狗）
应避免使用the both, 应当用the two,
如：The two of them were incited.
那两人被邀请了。（强调二人一起）
在正式英语中应用the two of you, 而不用you both,
如：Notice will be sent to the two of you.
通知将送交你们二位。
all, every ,each的比较
each 可指小到两个，all, every 则至少指三个。all 表所有项目的总和，是一不可分割的整体。
如：All the students contributed to the fund.
所有学生都为基金会捐了款。
every 是由各个项目集合成一个集体，其构成成分有共性。如：
Every student contributed to the fund.
所有学生都为基金会捐了款。
each的注意力集中在个别项目上，其构成成分各具特性。如：
Each student contributed to the fund.
每个学生都为基金会捐了款。