bbbb bbdd bbdo bd-r bobb bobo bobu bodb bodo bodu boko boku boob bood book boor bor- bord bork boro borr boru boud bouk bour brdo brkb brob brod brok broo bror brou brrr brud bubb bubo bubu budb budd budo budu bukk buko buku bur- burb burd burk buro burr buru d-bo dddd ddub dobb dobu dod- dodd dodo doko doob dood dook door dord dork doro dorr doru doub doud douk dour drob drod drou drub druk druu dub- dubb dubu dudd dudo dudu duku duo- durk duro duru duur kbbb kbbd kbbk kbbo kbbr kbbu kbdb kbdo kbdr kbkb kbkk kbko kbkr kbob kbod kbok kboo kbrb kbrd kbrk kbro kbru kbub kbud kbuk kbur kbuu kdbb kdbr kddb kddd kddk kddr kdkb kdkd kdkk kdko kdkr kdok kdrb kdro kdub kdur kkbb kkbd kkbo kkbr kkdd kkdo kkkk kkob kkoo kkor kkrb kkrk kkro kkrr kkuu kobb kobk kobo kobr kobu kodk kodo kodu kokb kokk koko kokr koku koob kook kooo koor koou korb kord kork koro korr koru koub kour kouu krbb krbd krbk krbr krdd krdo krdr krdu krkd krkk krko krkr krku krob krod krok kroo kror krrb krrk krro krrr kruk krur kubb kubd kubo kubr kubu kudd kudo kudu kukk kuku kuok kuoo kurb kurd kurk kuro kurr kuru kuub kuuk kuur kuuu obbo obkb obok obor obro odbo oddd odoo odor odou odur okko okok okor okro okur ooku oooo oord orbb orbo orbu ordo ordu orko oro- orok oror orro orub our- ouro ouu- rbbb rbbr rob- robb robo robu rodd rodo rokk roko rokr roku roob rood rook roor rork roro roru roub roud rouk rrrr rubb rubu rudd rudo rukk ruku ruok rurd ruro ruru ruud ubbo ubod ubud udoo uduk ukko ukok ukur uor- urdu uro- urok uroo uruk urur uuuu