bbbb bbfn bnor bnrr bobb bobo bobu boff bofu bonn bono bonu boob boof boon boor bor- borf born boro borr boru bouf boun bour brfu brno brob bron broo bror brou brrr brun bubb bubo bubu buff bufo bufr bunb bunn buno bunu buon bur- burb burn buro burr buru ffff ffrr ffun fnuf fofo fono foof foon for- forb forn foro forr foun four frob fron frou frub frun fubb fubu fuff fufu funf fuor fur- furn furo furr nbbo nbuf nfff nfon nnnn nobo nobu non- nonn nono nonu noo- noob noon nooo noor nor- norb norf norn noro norr noun nour nron nuff nunn nuno nuon nurn nurr nuru obbo obon obor obro off- offo offr offu ofno ofor onno onon onor onur ooff oooo orbb orbo orbu orff orfu orno oro- orof oron oror orro orub ouff oun- our- ourn ouro ouu- rbbb rbbr rnbr rob- robb robo robu roff rofo rono roob roof roon roor roro roru roub rouf roun rrrr rrun rubb rubu ruff rufo runf runn runo ruro ruru ruun ubbo ubon unno unon unrf unro uofo uor- urff uro- uroo urun urur uuno uuuu