bbbb bbpr bobb bobo bobu boob boop boor boot bopp bor- boro borr bort boru botb boto bott boup bour bout bpot brob broo bror brot brou brrr brup brut btbp btob btor btrt bttb bubb bubo bubu bur- burb buro burp burr burt buru but- buto butt obbo obor obot obro oooo oort ootb ootp opo- opor oppo opto orbb orbo orbu oro- oror orot orro orto orub orup oto- otoo otor otpp otro otto ottu otur our- ouro ourt out- outb outo ouu- pobo poop poor poot pop- popo popp popt porb poro porr port poto pott potu poup pour pout pppo pppp ppru pptt ppur pro- prob proo prop prot prou prtp prtr prut pruu ptop pubu pupu pur- purb puro purp purr puru put- puto putt putu rbbb rbbr rob- robb robo robt robu roob roop roor root ropo roro rort roru roto rotr rott roub roup rout rpob rrrr rttp rubb rubp rubu rupp rupt ruro rurp ruru ruto rutt rutu tbrb tbtp tobo tobt tobu toor toot top- topo topp topt topu toro torp torr tort toru toto totr tott toup tour tout tppp tppr tptp tptr tput troo trop trot trou trpp trtr trub trut truu ttbb ttop tttt tubb tubo tubr tubu tuor tupo tupu turb turo turp turr turt turu tuto tutt tutu tuuo u-rp ubbo uor- upor uppp uppu upto upup uro- uroo urpo urup urur urut utor utto uttu uuuu