-ous bbbb bbbs bffs bfts bftt bobb bobo bobs bobu boff bofs bofu boob boof boos boot boso boss bost bosu botb boto bots bott bouf bous bout bsff bsfs bsos bsts btob btss bttb btus bubb bubo bubs bubu buff bufo buss bust busu but- buto buts butt buus fbus ffff ffss fftf fobs fobt fofo foof foos foot fosb foso foss fost foto fots fott fous fout fsfo fssf ftos ftub fubb fubs fubu fuff fufu fuso fuss fust fusu futo futs futu obbo obos obot obss obst obts obus off- offo offs offu ofst ofus ooff oofs oooo ooos oost ootb oots oous osoo osos ossb osso ossu osts otbs oto- otof otoo otos otso otsu otto otts ottu otus oubs ouff oust out- outb outo outs ouu- s-os sbbs sbot sbst sbus sfos sfss sfsu sfts sobo sobs sobt sobu sofo soft soof soos soot soso soss sost soto sots sotu souf sous sout ssot sssb sssf ssss sstb ssts stbs stfu stob stof stoo stos stot stou stsf stss stub stuf stus stut sub- subb subo subs suf- suff sufs sufu suos sus- suso suss sust susu suto sutu suus tbbs tbst tfot tfss tobo tobs tobt tobu toff tofo toft tofu toof toos toot tosb toso toss tost tosu toto tots tott tous tout tsob tsos tsou tssf tsst tsts ttbb ttff ttss tttt tubb tubo tubs tubu tuff tufo tuft tufu tuos tuss tust tuto tuts tutt tutu tuuo ubbo ubos ubtf ufos uofo usbs usfs usos ussb ussf usss usst ussu ustb usto usts usus utfo utto uttu uutf uuuu