bbb bbi bbo bbs bbt bbx bi- bib bii bio bis bit bix bob boi boo bos bot box bsb bsi bso bss bst bsx btb bti bto bts btt btx bxb bxi bxo bxx ibb ibi ibo ibs ibt ibx iib iii iio iis iit iix io- iob ioi ioo ios iot is- isb isi iso iss ist itb iti ito its itt itx ixi o-i ob- obb obi obo obs obt obx oib oii oio ois oit oo- oob ooi ooo oos oot oox os- osb osi oso oss ost osx ot- otb oti oto ots ott ox- oxb oxi oxo oxt oxx sbb sbi sbo sbs sbt sbx sib sii sio sis sit six sob soi soo sos sot sox ss- ssb ssi sso sss sst ssx stb sti sto sts stt stx sxi sxs sxt t-x tbb tbi tbo tbs tbt tib tii tio tis tit tix to- tob toi too tos tot tox tsb tsi tso tss tst tsx ttb tti tto tts ttt ttx txi txs txt xbx xii xio xis xit xix xoi xoo xos xot xox xsb xsi xss xst xti xts xtx xxi xxo xxx