-tree bbbee be-er beber beebe beeft beete beeut beffe befur berbe beret berre berru berte betee beter betre bett- bette beuer beure beute brebu breef breer breet brere brett breu- brrrr bruer bruet bruff brute btr-t bubbe buber bufet buffe buret burru burte burtt burut buter butte butut ebber ebbet ebert ebure eeeee ef-tu efere efetf effer effet efter efuru efutu erbbe erber erere errtu erte erter etete etree etter eturu eurre febre feere feret ferr- ferre ferte feter fette feuer feute freer freet frere frett freur frute ftrtt fu-fu futur rebbe reber rebet rebut reefe reeft reere refer refet reffe refut rere- reree reret retee reter rette reuer reuet reute rubee ruber ruere ruete ruffe ruter rutte ruutu tbtbt tbutt teber tebet tefe teret tereu terre tert- teter tetr- tette treer treet trefe treff trere trete trett treut trubu truer truff trute ttttt tuber tuffe tufte turbe turbt turet turre turtu turut tutee tutte tuuru uber- ufere urter urubu urutu uter- utter uttur utube uturu uuuuu