请教几道语法，谢谢哈

苹果宝宝UID: 2123543

1，Each (of functions)( of the body),even thinking ,requires (the expenditure)   ( of energy ).

A

2,B acteria and (simila)r one-celled organisms reproduce by cell division,each  of    the daughter (cell )then (beginning) a new life (as) a distince organism.
B
前一题说EACH OF后面跟的是单数，后面一题又说加复数，那应该如何？在什么情况下EACH OF后面跟复数？
3，Grourds were (introduced) to what is now the  southwestern United States  by (earilest) peoples (who) migrated north (from) Mesoamerica about 700 years   ago.
B
王海波的语法笔记里有说EARILEST有作形容词的用法，可是这里为什么不对了？那应该什么时候那能理解为是做adj.的？
谢谢各位GGJJ了恩