But in the intermediate and advanced stages, progress is less obvious and painfully slow, if not invisible altogether.
便濫了.便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了便濫了