bbbb bbbs bobb bobo bobs bomb boms boob boom boor boos bor- borm boro borr bors bosm boso boss brob brom broo bror bros brrm brrr brrs brsb brsr bsms bsos bsrm bssm mbbs mbms mbrs mmmm mmms mmor mobb mobo mobs momo moms moob moor moos morb moro mors moso moss mrbb mrbm mrbs msmb msmm msms msor msrb mssm mssr obbo obor obos obro obsr obss ombo omo- omoo omor omro ooms oooo ooos orbb orbo orbs ormo oro- orom oror oros orro orrs orso osm- osmo osoo osor osos osro ossb osso rbbb rbbr rbbs rbms rbss rmbs rob- robb robo robs romb romm romo roms roob room roor roos roro roso ross rrrr rsos s-os sbbs sbor smos smss sobo sobr sobs somb somm somo soom soor soos sorb sorm soro sorr sors soso soss sros ssbr ssrm ssrs sssb sssm ssss