up = u-p
up
cup = c-u-p
cup
luck = l-u-ck
luck
pup = p-u-p
pup
gull = g-u-ll
gull
cuff = c-u-ff
cuff
but = b-u-t
but
muff = m-u-ff
muff
nut = n-u-t
nut
mutt = m-u-tt
mutt
tuck = t-u-ck
tuck
hull = h-u-ll
hull
mud = m-u-d
mud
duck = d-u-ck
duck
huff = h-u-ff
huff
ruff = r-u-ff
ruff
rut = r-u-t
rut
buzz = b-u-zz
buzz
hut = h-u-t
hut
cut = c-u-t
cut
muck = m-u-ck
muck
bud = b-u-d
bud
fuzz = f-u-zz
fuzz
dull = d-u-ll
dull