on april twenty would like to fly from denver to pittsburgh at about 8 o'clock in the morning
O B-depart_date.month_name B-depart_date.day_number O O O O O B-fromloc.city_name O B-toloc.city_name O B-depart_time.time_relative B-depart_time.time I-depart_time.time O O B-depart_time.period_of_day