Translation of "Perfected" in Chinese

That's the true genius of America; that America can change. Our Union can be perfected. What we've already achieved gives us hope for what we can and must achieve tomorrow.

这才是美国真正的精华——美国能够改变。我们的联邦会日渐完美。我们现在已取得的成就为我们将来能够取得和必须取得的成就增添了希望。