o bai bai bai bai
o bai bai bai bai .
o WORD_BOUNDARY β ai̯ WORD_BOUNDARY β ai̯ WORD_BOUNDARY β ai̯ WORD_BOUNDARY β ai̯ WORD_BOUNDARY
o WORD_BOUNDARY b a i WORD_BOUNDARY b a i WORD_BOUNDARY b a i WORD_BOUNDARY b a i WORD_BOUNDARY . WORD_BOUNDARY