aa1 aa1 俾 aa3
aa1 aa1 bei2 aa3
fil fil prep fil
aa1 aa1 俾 aa3 .
a̞˥ WORD_BOUNDARY a̞˥ WORD_BOUNDARY p ei˧˥ WORD_BOUNDARY a̞˧ WORD_BOUNDARY
a a 1 WORD_BOUNDARY a a 1 WORD_BOUNDARY 俾 WORD_BOUNDARY a a 3 WORD_BOUNDARY . WORD_BOUNDARY