bbbb bnor bnrr bobb bobo bobu bonn bono bonu boob boon boor booz bor- born boro borr boru borz boun bour bozo brno brob bron broo bror brou broz brrr brun bruz bubb bubo bubu bunb bunn buno bunu bunz buon bur- burb burn buro burr buru burz buuz buzz bzou bzzz nbbo nnnn nobo nobu non- nonn nono nonu noo- noob noon nooo noor nor- norb norn noro norr noun nour nron nunn nuno nuon nurn nurr nuru nzrb obbo obon obor obro onno onon onor onoz onur onzo oooo orbb orbo orbu orno oro- oron oror oroz orro orub orzo orzu oun- our- ourn ouro ouu- ouzo ozon ozun rbbb rbbr rnbr rob- robb robo robu rono roob roon roor rooz roro roru roub roun rouz rozz rrrr rrun rubb rubu runn runo ruro ruru ruun ubbo ubon unno unon unro unuz uor- uro- uroo urun urur uruz uuno uuuu uzon uzun z-ro zobo zon- zoo- zoon zorb zorn zoro zozo zozu zubo zubr zubu zunz zuoz zurb zurn zurr zuru zuun zuzu zzzz