-er -ol bbb bbe bbk bbl bbo bbr bbs be- beb bee bek bel beo ber bes bkb bke bkk bkl bko bkr bks blb ble blk bll blo blr bls bob boe bok bol boo bor bos brb bre brk brl bro brr brs bsb bse bsk bsl bso bsr bss ebb ebe ebk ebl ebo ebr ebs eeb eee eek eel eeo eer ees ekb eke ekl eko ekr eks elb ele elk ell elo elr els eo- eob eoe eok eol eoo eor eos erb ere erk erl ero err ers es- esb ese esk esl eso esr ess kbb kbe kbk kbl kbo kbr kbs ke- keb kee kek kel keo ker kes kkb kke kkk kkl kkr kks kl- klb klo klr kls kob koe kok kol koo kor kos krk krl kro krr krs ksb kse ksk ksl kso ksr kss lbb lbe lbk lbl lbo lbr lbs leb lee lek lel leo ler les lkb lkl lkr lks llb lle llk lll llo llr lls lob loe lok lol loo lor los lrb lrk lro lrr lrs lsb lse lsk lsl lso lsr lss ob- obb obe obk obl obo obr obs oeb oee oel oeo oer oes okb oke okk okl oko okr oks olb ole olk oll olo ols oo- oob ook ool ooo oor oos or- orb ore ork orl oro orr ors os- osb ose osk osl oso osr oss rbb rbe rbk rbl rbo rbr rbs re- reb ree rek rel reo rer res rkb rke rkk rko rks rle rll rlo rlr rls rob roe rok rol roo ror ros rrb rrk rrl rrr rrs rsb rse rsk rsl rso rsr rss sbb sbe sbk sbl sbo sbr sbs se- seb see sek sel seo ser ses sk- skb ske skk skl sko skr sks slb sle slk sll slo slr sls sob soe sok sol soo sor sos sr- srb sre srk srl sro srr srs ss- ssb sse ssk ssl sso ssr sss