bbbb bbbs bibb bibi bibo bibs biis bio- bioi bios biot birb biri biro birr birs birt bis- biso biss bist bito bits bitt bivi bobb bobi bobo bobs boi- boii bois boit boob boor boos boot bor- bori boro borr bors bort bosi boso boss bost botb boti boto bots bott bovi bovo brio bris brit brob broo bror bros brot brrr brrs brsb brsr brst brvi bsos bsts bstv btob btor btrt btss bttb btvi ibis ibos ibot ibri ibro ibss ibtb ibts iiii iiio iiis iiit iioi iioo iios iirs iisi iisr iist iitr iitt iobi ioii ioio ioit iooi iooo ioos iori iors ioso ioto iri- irio iris irob irov irri irrs irti irts irvs isbt isis isit iso- isor isos isri issi isso issr isss isti isto istr ists itbs itis itoi itoo itor itos itri itrs itsi itso itto ivbv ivor ivrs obbo obis obit oboi obor obos obot obri obro obsr obss obst obts obvi obvs oiii oios oirt oist oiti oobi oooo ooos oort oosi oost ootb oots orbb orbi orbo orbs ori- orio oris orit oro- oror oros orot orri orro orrs orsi orso orto orts orvr orvs osii osis osoi osoo osor osos osov osro ossb ossi osso osti ostr osts otbs otis otit oto- otoo otor otos otov otro otrs otso otti otto otts ovi- ovis ovo- ovoo ovot rbbb rbbr rbbs rbis rbss rbst rib- ribo ribs riis rios riot riri rirs risi riso riss rist riti rito rits ritt rivo rivs rob- robb robi robo robs robt roio roir rois roit roob rooi roor roos root rori roro rort rosi roso ross rost roti roto rotr rots rott rovi rovo rovs rrrr rsbi rsis rsos rsts rtss rtts rtvi s-ib s-ii s-iv s-os s-vt sbbs sbor sbot sbsi sbst sibi sibo sibs siit sior sios siot siri siro sirr sirs sirt sisi siss sist sit- siti sito sits sitt sivi sobo sobr sobs sobt soir sois soit soor soos soot sorb sori soro sorr sors sort sosi soso soss sost sosv soto sots sovo sovs srib sris sros srtr srtv ssbr ssis ssit ssot ssri ssrs sssb sssi ssss sstb ssts st-v stbs stib stio stir stis stit stob stoo stor stos stot stri stro strs stsi stss sttr stvs svir svit svor svtr tbbs tbit tbrb tbst tbvi tibi tibs tiit tios tirb tiri tiro tirr tirs tisb tisi tiso tiss tist titi tito tits titt tivi tivo tobi tobo tobs tobt tois toit toor toos toot tori toro torr tors tort torv tosb tosi toso toss tost toti toto totr tots tott tovo tri- trib trio tris trit troi troo tros trot trsi trst trtr trvs tsis tsiv tsob tsoi tsos tssi tssr tsst tsts tsvi ttbb ttss tttt tvbs tvis tvos tvri tvro tvrr tvss tvtv vibs viii vios virb viri viro virr virt visi viso viss vist viti vito vitt vivi vivo voio voir vois voit voor voot vor- vori voro vors vort vosi voso voss voto vrio vris vrot vrsi vrto vsto vt-i vtrs vvob vvsb vvvv