-tree b-r-k bbbee be-er bebek beber beebe beeke beete beeut beker bekke berbe berek beret berk- berke berre berru berte betee beter betke betre bett- bette beuer beure beute brebu breek breer breet breke brere brett breu- brrrr bruer bruet bruke brute btr-t bubbe buber buker buket bukk- burek buret burke burru burte burtt buruk burut buter butke butte butut ebber ebbet ebert ebure eeeee ekker ekuku ekuru erbbe erber erere errtu erte erter eruke eteke etete etree etrek etter eturu eurre k-t-b k-ute kebbe kebek keber keere kerek keret kerre kertu ketek keter kette kreek kreke krete kreuk kubek kuber kukur kurbu kurek kurku kurre kurte kuruk kutte kuttu kutur rebbe reber rebet rebut reere rekke rere- reree reret retee reter rette reuer reuet reute rt-rk rubee ruber rubke ruere ruete rukke ruter rutte ruutu tbtbt tbutt teber tebet tebuk teket tekke terek teret tereu terre tert- teter tetr- tette trbuk treer treet trere trete trett treut trubu truer truke trute ttttt tubek tuber tukur turbe turbt turek turet turku turre turtu turut tutee tutku tutte tuuru uber- ukeke ukert urker urkut urter urubu urutu uter- utter uttur utube uturu uuuuu