-tree bbbee be-er bebel beber beebe beeft beele beete beeut beffe befur belee belef belet bellb belle belue belur belut berbe berel beret berle berre berru berte betee betel beter betle betre bett- bette betul beuer beule beure beute bleer bleet bleft blere blete bleue bluer bluet bluff blufr bluft blurb blure blurr blurt brebu breef breel breer breet brell brere brett breu- brrrr bruer bruet bruff brule brull brute btr-t bubbe buber buble buell bufet buffe bufle bulb- bull- bulle bulul bulut burel buret burle burru burte burtt burut buter butle butte butut ebber ebbet ebble ebell eberl ebert eblul ebull ebure eeeee eeler ef-tu efere efetf effer effet eftel efter efuru efutu eleet elele eleut ellel eller ellet ellul elulu eluru elute erbbe erber erere errtu erte ertel erter etete etree ettel etter ettle eturu euell euler eurel eurre febel feble febre feele feere felet felle felte feltt ferel feret ferle ferr- ferre ferte fetel feter fette feuer feule feute fleer fleet flere flert flete flett fleur fluff flurb flure flurr flurt flute freel freer freet frere frett freur frute ft-lb ftlee ftrtt fu-fu fulbe fulle fullf furel futur lebel leber lebet leell leere leert lefeu leffe leftb leful leleu lelle lerer letbe letre lette letur lubbe luber luble lubur lufre lufte lulle lulte lulul lurer lurue lute- luter lutte rebbe rebel reber rebet rebut reefe reeft reere refel refer refet reffe refut relee relet relte relue rere- reree reret retee retel reter rette reuel reuer reuet reule reute rubee rubel ruber ruble ruele ruell ruere ruete ruffe ruler ruter rutle rutte rutul ruule ruutu tbtbt tbutt teber tebet teele teell tefe tele- teler teleu tell- telle teret tereu terre tert- tetel teter tetle tetr- tette tlell tlett tllbr treer treet trefe treff trele trere trete trett treut trubu truel truer truff trule trull trute ttttt tuber tubul tuelf tuell tuelt tuffe tufte tulet tulle turbe turbt turel turet turle turre turtu turul turut tutee tutel tutle tutte tuuru ubble uber- uelfe ufere ullet ullur ultre ululu uluru urelu urtel urter urtlu urubu urutu uter- utter uttur utube uturu uuuuu