Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.

Now we are engaged in a great civil war, testing whether that nation or any nation so conceived and so dedicated, can long endure.

请问老师，are created equal 中 equal 是形容词作什么成分呢？另外 so conceived and so dedicated 中的2个so 是指代什么呢？