-tree bbbee be-er be-ro beber bebot beebe beete beote berbe beret berob beroe beror berre berte berto betee beter betoo betor betre bett- bette betto bo-bo bobet bobr bobre boero booer boore boort borbo boree borer boro- boroo borot borre borro botet botro botte breer breet breo- brere breto brett brobo broer broto brrrr btr-t ebber ebbet ebert eeeee eorre erbbe erber erere eroor erore eroto error erte erter etete etoro etree etter o-r-b obbet obert obete oboro obote obreb oo-er ooooo orbot oreo- orere orero orobe orobo oroer orret orter ortet ortoo otere otero ototo otter rebbe reber rebet reere rere- reree reret rerob retee reter retro rette retto ro-ro robbe robbo rober robo- robor robot robrt robte roero rooer roore roote rorer roteb roter roto- rotor rotot rotte rotto tbtbt teber tebet teret teror terre terro tert- teter tetr- tetro tette to-be tobbe tober tobet tobor tobot tobre toerr toeto toobe toore torbe toreo toret torob torre torro torte torto toter toto- totoe totoo totte treer treet trere trete trett troee trott ttttt