bbbb bibb bibi bibo biko bio- bioi biot birb biri birk biro birr birt bito bitt bobb bobi bobo boi- boii boit boki boko boob book boor boot bor- bori bork boro borr bort botb boti boto bott brik brio brit brkb brob brok broo bror brot brrr btob btor btrt bttb ibot ibri ibro ibtb iiii iiio iiit iioi iioo iitr iitt ikki ikko ikoo ikri iobi ioii ioio ioit ioko iooi iooo iori ioto iri- irio irki irob irri irti itko itoi itoo itor itri itto kbbb kbbi kbbk kbbo kbbr kbbt kbib kbik kbio kbit kbkb kbkk kbko kbkr kbob kboi kbok kboo kbot kbrb kbri kbrk kbro kbrt kbtb kbtk kbto kbtr kbtt kibb kibi kibo kibr kibt kiii kiik kiit kiki kikk kiko kikr kikt kioi kiok kioo kiot kirb kiri kirk kiro kirr kirt kiti kito kitr kitt kkbb kkbi kkbo kkbr kkbt kkik kkit kkkk kkob kkoo kkor kkot kkrb kkrk kkro kkrr kkrt kktk kobb kobi kobk kobo kobr koii koir koit kokb koki kokk koko kokr koob kooi kook kooo koor koot korb kori kork koro korr kort kotb koti kotk koto kotr kott krbb krbi krbk krbr krbt krib krik krio krit krki krkk krko krkr krob kroi krok kroo kror krrb krri krrk krro krrr krrt krti krtk krto krtr ktbb ktbr ktbt ktib ktik ktkb ktkk ktko ktkr ktkt ktob ktok ktoo ktor ktot ktrb ktri ktrk ktro ktrr ktrt ktti kttk ktto kttr kttt obbo obit obkb oboi obok obor obot obri obro oiii oiko oirt oiti okir okko okok okor okot okro okto oobi oooo oort ootb orbb orbi orbo ori- orio orit orko oro- orok oror orot orri orro orto otit oto- otok otoo otor otro otti otto rbbb rbbr rib- ribo riki rikk riot riri riti rito ritt rob- robb robi robo robt roik roio roir roit roki rokk roko rokr roob rooi rook roor root rori rork roro rort roti rotk roto rotr rott rrrr tbit tbrb tibi tiit tiki tiko tirb tiri tiro tirr titi tito titt tobi tobo tobt toit toki toko took toor toot tori tork toro torr tort toti toto totr tott tri- trib trik trio trit troi troo trot trtr ttbb tttt