I haven't seen this
I have see this
pro:sub aux part pro:dem
i haven't seen this .
aɪ WORD_BOUNDARY h a v ə n t WORD_BOUNDARY s iː n WORD_BOUNDARY ð ɪ s WORD_BOUNDARY
i WORD_BOUNDARY h a v e n ' t WORD_BOUNDARY s e e n WORD_BOUNDARY t h i s WORD_BOUNDARY