-er -ey b-u bbb bbe bbr bbu bbx bby be- beb bee ber beu bex bey brb bre brr bru brx bry bub bue bur buu bux buy bxb bxx by- bye byr byu ebb ebe ebr ebu ebx eby eeb eee eer eex eey erb ere err eru ery eu- eub eue eur eux ex- exe exr exu exx exy eye eyr rbb rbe rbr rbu rbx re- reb ree rer reu rex rey rrb rrr rru rub rue rur ruu rux ruy rxr ry- rye ryr ryu ryy ubb ube ubr ubu ubx uby ueb uee uer uey ur- urb ure urr uru urx ury uue uur uuu uxb uxr uxu uyu xbe xbr xbx xee xer xeu xex xrx xry xue xxx xxy xyr xyy ybe ybr yby yeb yee yer yex yey yre yru yue yur yuu yux yuy yxe yxy yyb yye yyu yyy