-tree bbbee be-er be-ro beber bebot beebe beete beeut beote beour berbe beret berob beroe beror berre berru berte berto betee beter betoo betor betou betre bett- bette betto beuer beure beute bo-bo bobet bobr bobre boero boeur booer boore boort booru borbo boree borer boret boro- boroo borot borou borre borro borut botet botou botro botte bottu bouee bouer bouet boure boute bouto brebu breer breet breo- brere breto brett breu- brobo broer broto broue brout brrrr bruer bruet brute btr-t bubbe buber buret buroo burro burru burte burtt burut buteo buter buto- butor butot butou butte butuo butut ebber ebbet ebert eboue ebure eeeee eorre erbbe erber erere eroor erore eroto error errtu erte erter etete etoro etour etree etter eturu eubro euro- eurre o-r-b obbet obert obete oboro obote oboue obout obreb oo-er ooooo orbot oreo- orere orero orobe orobo oroer orout orret orter ortet ortoo orube oruro orutu otere otero ototo otour otter ottur oture oubut ouert ouoro oure- outer outre outro outto rebbe reber rebet rebut reere rere- reree reret rerob retee reter retro rette retto reuer reuet reute ro-ro robbe robbo rober robo- robor robot robrt robte robur roero rooer roore roote rooue rorbu rorer roteb roter roto- rotor rotot rotte rotto roubt rouer rouet roure route routt rubee ruber rubor ruere ruete ruter rutte ruutu tbtbt tbutt teber tebet teret tereu teror terre terro tert- teruo teter tetr- tetro tette teuto to-be tobbe tober tobet tobor tobot tobou tobre toerr toeto toobe toore torbe toreo toret torob torre torro torte torto tortu torue toter toto- totoe totoo totte toure touro toute treer treet trere trete trett treut troee trott troue trout trubu truer truro trute ttttt tuber tubo- tubou tuero tuotu turbe turbo turbt turet turot turre turro turtu turut tutee tuteo tutor tutte tutto tuuru uber- ubobo uouee ureo- uroob urour urter urubu urutu utebo uter- utero utro- utror utter uttur utube uturu ututo uuuuu