    Sentence. “1 Because. several’ passengers’, on  Unitéd 93. described. three ‘hijackers: on. “the  plane,: not: four, some: have wvondered whetlier  lone of' the ,hijackers had been able to; use- the  cockpit jump Seat fronx the outset of the flight.    Sentence 2: ‘There-.was_a- dispuite. over’: the  number of hijackers on-the. phane: