since all men are created ____,we have the right to fight for equality.

created equal是生而平等
created equally是平等地生
用语法上说，be created equal是系表结构，后面两个都是形容词，一个是created“被创造的”，分词作equal的形容词。
而created equally就不同了，那就是equally作副词，修饰动词created,就是被动语态了！