-er a-a a-b a-t aaa aab aae aar aat aau aax ab- aba abb abe abr abt abu abx aea aeb aee aer aet aeu aex ar- ara arb are arr art aru arx at- ata atb ate atr att atu atx au- aua aub aue aur aut aux ax- axa axe axr axt axx b-u baa bab bae bar bat bau bax bba bbb bbe bbr bbt bbu bbx be- bea beb bee ber bet beu bex bra brb bre brr brt bru brx bta btb bte btr btt btu btx bua bub bue bur but buu bux bxb bxx eaa eab eae ear eat eau eax eba ebb ebe ebr ebt ebu ebx eea eeb eee eer eet eex era erb ere err ert eru eta etb ete etr ett etu etx eu- eua eub eue eur eut eux ex- exa exe exr ext exu exx ra- raa rab rae rar rat rau rax rba rbb rbe rbr rbt rbu rbx re- rea reb ree rer ret reu rex rra rrb rrr rrt rru rta rtb rte rtr rtt rtu rtx rua rub rue rur rut ruu rux rxr t-x taa tab tae tar tat tau tax tba tbb tbe tbr tbt tbu te- tea teb tee ter tet teu tex tra trb tre trr trt tru trx tta ttb tte ttr ttt ttu ttx tua tub tue tur tut tuu tux txe txt txu ua- uaa uab uae uar uat uau uba ubb ube ubr ubt ubu ubx uea ueb uee uer uet ur- ura urb ure urr urt uru urx uta utb ute utr utt utu utx uua uue uur uut uuu uxb uxr uxt uxu xaa xar xat xau xbe xbr xbx xee xer xet xeu xex xrt xrx xtr xtx xue xxx