bbbb bnor bnrr bobb bobo bobu bonn bono bont bonu boob boon boor boot bor- born boro borr bort boru botb botn boto bott boun bour bout brno brob bron broo bror brot brou brrr brun brut btob btor btrt bttb bubb bubo bubu bunb bunn buno bunt bunu buon bur- burb burn buro burr burt buru but- buto butt nbbo nnnn nnot nntn nobo nobu non- nonn nono nont nonu noo- noob noon nooo noor noot nor- norb norn noro norr nort not- noto nott noun nour nout nron ntnu ntru ntto nttr nunn nuno nunt nuon nurn nurr nurt nuru nutt nutu obbo obon obor obot obro onno onon onor ont- onto onur onut oont oooo oort ootb orbb orbo orbu orno oro- oron oror orot orro orto orub oto- oton otoo otor otro otto ottu otur oun- our- ourn ouro ourt out- outb outo ouu- rbbb rbbr rnbr rnnt rnot rnut rob- robb robo robt robu rono ront roob roon roor root roro rort roru rotn roto rotr rott roub roun rout rrrr rrun rubb rubu runn runo runt ruro ruru ruto rutt rutu ruun tbrb tnut tobo tobt tobu tonb tonn tono tonu toon toor toot torn toro torr tort toru toto totr tott toun tour tout trno tron troo trot trou trtr trub trun trut truu ttbb tton tttt tubb tubo tubr tubu tunb tunn tuno tunu tuor turb turn turo turr turt turu tuto tutt tutu tuuo ubbo ubon unno unon unro untb unto unut uor- uro- uroo urun urur urut utor utto uttu uuno uuuu