bbbb bbeb bbet bebb bebe bebo beeb beer beet beo- beor beot bere bero berr bert beru bete beto bett betu beur bobb bobe bobo bobu boee boeo boer boet boob booe boor boot bor- bore boro borr bort boru botb bote boto bott boue bour bout breb bree breo brer bret brob broe broo bror brot brou brrr brue brut btob btor btrt bttb bubb bube bubo bubu buer bueu bur- burb bure buro burr burt buru but- bute buto butt ebbo ebbr eber eboe eboo ebor ebro ebru ebur eeee eero eete eetu eore eoto erbb erbe ereb erer eret erob eroe eroo erre erro ertu erub erur etbr etee eter etoe etre etro ette etto ettu euer eur- eure euro eurt o-eo obbo ober obet oboe obor obot obre obro oere oobe ooer oooo oore oort ootb orbb orbe orbo orbu ore- oreb oreo orer oro- oroe oror orot orro orte orto orub otee oter oto- otoe otoo otor otre otro otte otto ottu otur ouer our- oure ouro ourt out- outb oute outo ouu- rbbb rbbr rebb rebe rebo rebu reeb reet reot reou rere rero rert reru rete reto retr rett reue reut reuu rob- robb robe robo robt robu roer roet roob roor root rore roro rort roru rote roto rotr rott roub roue rout rrrr rtee rubb rube rubu ruer ruet rure ruro ruru rute ruto rutt rutu tbrb tebo tebu teer teet teor ter- tere tero terr teru tete teto tetr tett tetu teut tobe tobo tobt tobu toee toer toet toor toot tore toro torr tort toru tote toto totr tott tour tout tre- tree treo tret treu troe troo trot trou trte trtr trub true trut truu ttbb tteo tter ttoe tttt tubb tube tubo tubr tubu tuer tuet tuor turb ture turo turr turt turu tute tuto tutt tutu tuuo ubbe ubbo uber ubet uor- uore urbe ure- uret uro- uroo urre urte urur urut uter utor utto uttu uuuu