-er bbb bbe bbo bbr bbt bbx be- beb bee beo ber bet bev bex bob boe boo bor bot bov box brb bre bro brr brt brv brx btb bte bto btr btt btv btx bvb bve bvo bvr bvt bvv bxb bxo bxx ebb ebe ebo ebr ebt ebv ebx eeb eee eeo eer eet eev eex eo- eob eoe eoo eor eot erb ere ero err ert erv etb ete eto etr ett etv etx evb eve evo evr evt evv ex- exe exo exr ext exx ob- obb obe obo obr obt obv obx oeb oee oeo oer oet oex oo- oob ooo oor oot oov oox or- orb ore oro orr ort orv orx ot- otb ote oto otr ott otv ov- ovb ove ovo ovv ox- oxb oxo oxt oxx rbb rbe rbo rbr rbt rbx re- reb ree reo rer ret rev rex rob roe roo ror rot rov rox rrb rrr rrt rtb rte rto rtr rtt rtv rtx rvb rve rvo rvr rvt rvv rxr t-x tbb tbe tbo tbr tbt tbv te- teb tee teo ter tet tev tex to- tob toe too tor tot tov tox trb tre tro trr trt trv trx ttb tte tto ttr ttt ttv ttx tvb tve tvo tvr tvt tvx txe txt v-e vbo vbr vbv veb vee veo ver vet vex vob voe voo vor vot vov vox vrb vre vrr vrt vtb vte vto vtr vtt vtv vtx vvb vvo vvr vvt vvv vxr vxv xbe xbr xbx xee xer xet xev xex xoo xor xot xov xox xrt xrx xtr xtv xtx xvt xxo xxv xxx