-er bbb bbe bbm bbr bbs bbt bbx be- beb bee bem ber bes bet bex bmb bme bmm bmr bms bmt bmx brb bre brm brr brs brt brx bsb bse bsm bsr bss bst bsx btb bte btm btr bts btt btx bxb bxm bxx ebb ebe ebm ebr ebs ebt ebx eeb eee eem eer ees eet eex em- emb eme emm emr ems emt emx erb ere erm err ers ert es- esb ese esm esr ess est esx etb ete etm etr ets ett etx ex- exe exr exs ext exx m-r mbb mbe mbm mbr mbs mbt mbx meb mee mem mer mes met mex mmb mme mmm mmr mms mmt mmx mrb mre mrm mrr mrs mrt mrx msb mse msm msr mss mst msx mtb mte mtm mtr mts mtt mtx mxr mxs rbb rbe rbm rbr rbs rbt rbx re- reb ree rem rer res ret rex rmb rme rmm rmr rms rmt rmx rrb rrm rrr rrs rrt rsb rse rsm rsr rss rst rsx rtb rte rtm rtr rts rtt rtx rxr rxs sbb sbe sbm sbr sbs sbt sbx se- seb see sem ser ses set sex smb sme smm smr sms smt smx sr- srb sre srm srr srs srt srx ss- ssb sse ssm ssr sss sst ssx stb ste stm str sts stt stx sxm sxs sxt t-x tbb tbe tbm tbr tbs tbt te- teb tee tem ter tes tet tex tmb tme tmm tmr tms tmt tmx trb tre trm trr trs trt trx tsb tse tsm tsr tss tst tsx ttb tte ttm ttr tts ttt ttx txe txs txt xbe xbr xbx xee xem xer xes xet xex xmm xmr xms xmt xmx xrt xrx xsb xsm xss xst xtm xtr xts xtx xxx