-ous bbbb bbbs bobb bobo bobs bobu boob boor boos boot bor- boro borr bors bort boru boso boss bost bosu botb boto bots bott bour bous bout brob broo bror bros brot brou brrr brrs brsb brsr brst brus brut bsos bsts btob btor btrt btss bttb btus bubb bubo bubs bubu bur- burb buro burr burs burt buru buss bust busu but- buto buts butt buus obbo obor obos obot obro obsr obss obst obts obus oooo ooos oort oost ootb oots oous orbb orbo orbs orbu oro- oror oros orot orro orrs orso orsu orto orts orub orus osoo osor osos osro ossb osso ossu ostr osts otbs oto- otoo otor otos otro otrs otso otsu otto otts ottu otur otus oubs our- ouro ours ourt oust out- outb outo outs ouu- rbbb rbbr rbbs rbss rbst rob- robb robo robs robt robu roob roor roos root roro rort roru roso ross rost roto rotr rots rott roub rous rout rrrr rsos rsts rstu rtss rtts rubb rubs rubu ruro rurs ruru ruso russ rust rusu ruto ruts rutt rutu s-os sbbs sbor sbot sbst sbus sobo sobr sobs sobt sobu soor soos soot sorb soro sorr sors sort soru soso soss sost soto sots sotu sour sous sout sros srtr srub ssbr ssot ssrs sssb ssss sstb ssts stbs stob stoo stor stos stot stou stro strs stru stss sttr stub stur stus stut sub- subb subo subs suor suos sur- suro surr surs surt suru sus- suso suss sust susu suto sutu suus tbbs tbrb tbst tobo tobs tobt tobu toor toos toot toro torr tors tort toru tosb toso toss tost tosu toto totr tots tott tour tous tout troo tros trot trou trst trtr trub trus trut truu tsob tsos tsou tssr tsst tsts ttbb ttss tttt tubb tubo tubr tubs tubu tuor tuos turb turo turr turs turt turu tuss tust tuto tuts tutt tutu tuuo ubbo ubos uor- urbs uro- uroo urso urss ursu urts urur urus urut usbr usbs usos ussb ussr usss usst ussu ustb usto usts usus utor utto uttu uuuu