-er a-a a-b a-t aaa aab aae aak aar aas aat aax ab- aba abb abe abk abr abs abt abx aea aeb aee aek aer aes aet aex aka akb ake akk akr aks ar- ara arb are ark arr ars art arx as- asa asb ase ask asr ass ast asx at- ata atb ate atr ats att atx ax- axa axe axk axr axs axt axx baa bab bae bak bar bas bat bax bba bbb bbe bbk bbr bbs bbt bbx be- bea beb bee bek ber bes bet bex bka bkb bke bkk bkr bks bkt bkx bra brb bre brk brr brs brt brx bsa bsb bse bsk bsr bss bst bsx bta btb bte btk btr bts btt btx bxb bxx eaa eab eae eak ear eas eat eax eba ebb ebe ebk ebr ebs ebt ebx eea eeb eee eek eer ees eet eex eka ekb eke ekr eks ekt era erb ere erk err ers ert es- esa esb ese esk esr ess est esx eta etb ete etk etr ets ett etx ex- exa exe exr exs ext exx k-t ka- kaa kab kae kak kar kas kat kax kba kbb kbe kbk kbr kbs kbx ke- kea keb kee kek ker kes ket kex kkb kke kkk kkr kks kkt kra krk krr krs krt ksa ksb kse ksk ksr kss kst kta ktb kte ktk ktr kts ktt ra- raa rab rae rak rar ras rat rax rba rbb rbe rbk rbr rbs rbt rbx re- rea reb ree rek rer res ret rex rkb rke rkk rks rkt rra rrb rrk rrr rrs rrt rsa rsb rse rsk rsr rss rst rsx rta rtb rte rtk rtr rts rtt rtx rxr rxs saa sab sae sak sar sas sat sax sba sbb sbe sbk sbr sbs sbt sbx se- sea seb see sek ser ses set sex sk- ska skb ske skk skr sks skt skx sr- sra srb sre srk srr srs srt srx ss- ssa ssb sse ssk ssr sss sst ssx sta stb ste stk str sts stt stx sxs sxt t-x taa tab tae tak tar tas tat tax tba tbb tbe tbk tbr tbs tbt te- tea teb tee tek ter tes tet tex tka tkb tke tkk tkr tks tkt tra trb tre trk trr trs trt trx tsa tsb tse tsk tsr tss tst tsx tta ttb tte ttk ttr tts ttt ttx txe txk txs txt xaa xak xar xas xat xbe xbr xbx xee xer xes xet xex xkb xke xks xrt xrx xsa xsb xss xst xtr xts xtx xxx