bbbb bbdd bbdo bd-r bobb bobo bobu bodb bodo bodu boob bood boor boot bor- bord boro borr bort boru botb botd boto bott boud bour bout brdo brdt brob brod broo bror brot brou brrr brud brut btdt btob btor btrt bttb bubb bubo bubu budb budd budo budu bur- burb burd buro burr burt buru but- buto butt d-bo dbtt dddd ddot ddub dobb dobu dod- dodd dodo doob dood door doot dord doro dorr dort doru dotd doto dott doub doud dour dout drob drod drot drou drub drut druu dtor dtot dub- dubb dubu dudd dudo dudu duo- duro durt duru duur duut obbo obdt obor obot obro obtd odbo oddd odoo odor odot odou odtu odur oooo oord oort ootb orbb orbo orbu ordo ordu oro- oror orot orro orto orub otbd oto- otoo otor otro otto ottu otur our- ouro ourt out- outb outo ouu- rbbb rbbr rob- robb robo robt robu rodd rodo roob rood roor root roro rort roru roto rotr rott roub roud rout rrrr rtdt rubb rubu rudd rudo rurd ruro ruru ruto rutt rutu ruud tbrb tddb tdor tobo tobt tobu todd todo todt todu tood toor toot tord toro torr tort toru totd toto totr tott tour tout trod troo trot trou trtr trub trud trut truu ttbb tttt tubb tubo tubr tubu tudu tuor turb turd turo turr turt turu tuto tutt tutu tuuo ubbo ubod ubud udoo udot uor- urdu uro- uroo urur urut utor utto uttu uuuu