bbb bbi bbl bbs bbt bbx bi- bib bii bil bis bit bix blb bli bll bls blt blx bsb bsi bsl bss bst bsx btb bti btl bts btt btx bxb bxi bxl bxx ibb ibi ibl ibs ibt ibx iib iii iil iis iit iix il- ilb ili ill ils ilt ilx is- isb isi isl iss ist itb iti itl its itt itx ixi ixl lbb lbi lbl lbs lbt lbx lib lii lil lis lit lix llb lli lll lls llt lsb lsi lsl lss lst ltb lti ltl lts ltt ltx lxi lxx sbb sbi sbl sbs sbt sbx sib sii sil sis sit six slb sli sll sls slt slx ss- ssb ssi ssl sss sst ssx stb sti stl sts stt stx sxi sxl sxs sxt t-x tbb tbi tbl tbs tbt tib tii til tis tit tix tli tll tls tlt tlx tsb tsi tsl tss tst tsx ttb tti ttl tts ttt ttx txi txl txs txt xbl xbx xii xis xit xix xlb xli xls xlt xsb xsi xsl xss xst xti xts xtx xxi xxl xxx