Newton's third law says that every force X exerts onto Y, Y exerts and equal and opposite force onto X. Ergo, if I'm standing on my linoleum floor, I'm exerting a force equal to my weight (mass x force of gravity) onto the floor and it's exerting an equal and opposite force on to me. However, Newton also told us F=mA and that would mean that the force I am exerting on the floor, my weight, is equal to 0. (Assuming my downward acceleration is zero.) Though, as I mentioned, I am exerting my weight, w=mG and F=mA; Ergo if w=F then mG=mA and G=A. Can gravity really just be thought of as acceleration?