both 是"两者都" ,所以后面应该用名词复数,而且最好是两个的.
eg;both side of the street
each是”每一”,是指至少三个以上中的每一个,后面接名词单数．
eg.each student of the class
all 是全部,至少三个以上的全部,后面接名词复数或者不可数名词或单独用
eg.all the students & all the fish
either 是两者任一,后面直接接名词单数．或者可以单独用
eg.either of the two students
neither 是两者任一都不,用法基本同上．
eg.Neither of the two students got the highest score.