A Green Card holder who is not a minor can file Form N-400, Application for Naturalization, to obtain US citizenship. Similarly, he must have become a permanent resident before five years and must have remained as a permanent resident in America for at least five long years.
Now, flat paint is (usually) a latex paint that dries without a reflective finish-that's it-the finish is smoother (imho) than chalk paint. Chalk paint really dries quickly and it has a rough texture to it after it dries. Many people use wax or poly-acrylic sealant on top of their furniture piece to keep the paint from peeling. So there ya go, my best explanation.
A latex-based, versatile paint type, flat is normally used for walls and ceilings. Many types of finish are available: dead-flat matt, matt, a water-based eggshell and silk. Some formulations contain vinyl to make them more hardwearing. Flat is also best used on siding materials.