-al -ol a-a a-b a-t aaa aab aal aao aat ab- aba abb abl abo abt al- ala alb all alo alt aoa aob aol aoo aot at- ata atb atl ato att baa bab bal bao bat bba bbb bbl bbo bbt bla blb bll blo blt boa bob bol boo bot bta btb btl bto btt la- laa lab lal lao lat lba lbb lbl lbo lbt lla llb lll llo llt loa lob lol loo lot lta ltb ltl lto ltt oaa oab oal oao oat ob- oba obb obl obo obt ola olb oll olo olt oo- ooa oob ool ooo oot ot- ota otb otl oto ott taa tab tal tao tat tba tbb tbl tbo tbt tla tll tlo tlt to- toa tob tol too tot tta ttb ttl tto ttt