for half an hour
for half a hour
prep n det:art n
for half an hour.
f ɔ ɹ WORD_BOUNDARY h æ f WORD_BOUNDARY ʌ n WORD_BOUNDARY aʊ ə ɹ WORD_BOUNDARY
f o r WORD_BOUNDARY h a l f WORD_BOUNDARY a n WORD_BOUNDARY h o u r . WORD_BOUNDARY