4 letter words:
apos6,
apso6,
apts6,
atop6,
opts6,
past6,
pats6,
poas6,
post6,
pots6,
soap6,
spat6,
spot6,
stap6,
stop6,
taps6,
tops6,
oast4,
oats4,
stoa4,
taos4,
tosa4,
3 letter words:
apo5,
apt5,
asp5,
ops5,
opt5,
pas5,
pat5,
poa5,
pos5,
pot5,
pst5,
sap5,
sop5,
spa5,
tap5,
top5,
oat3,
sat3,
sot3,
tao3,
tas3,
2 letter words:
op4,
pa4,
po4,
as2,
at2,
os2,
so2,
st2,
ta2,
to2,