-ol bbb bbk bbl bbo bbs bbt bkb bkk bkl bko bks bkt blb blk bll blo bls blt bob bok bol boo bos bot bsb bsk bsl bso bss bst btb btk btl bto bts btt k-t kbb kbk kbl kbo kbs kkb kkk kkl kks kkt kl- klb klo kls klt kob kok kol koo kos kot ksb ksk ksl kso kss kst ktb ktk ktl kto kts ktt lbb lbk lbl lbo lbs lbt lkb lkl lks lkt llb llk lll llo lls llt lob lok lol loo los lot lsb lsk lsl lso lss lst ltb ltk ltl lto lts ltt ob- obb obk obl obo obs obt okb okk okl oko oks olb olk oll olo ols olt oo- oob ook ool ooo oos oot os- osb osk osl oso oss ost ot- otb otk otl oto ots ott sbb sbk sbl sbo sbs sbt sk- skb skk skl sko sks skt slb slk sll slo sls slt sob sok sol soo sos sot ss- ssb ssk ssl sso sss sst stb stk stl sto sts stt tbb tbk tbl tbo tbs tbt tkb tkk tkl tko tks tkt tlk tll tlo tls tlt to- tob tok tol too tos tot tsb tsk tsl tso tss tst ttb ttk ttl tto tts ttt