sustains interest during the long build-up of expository material 
(ROOT (S (VP (VBZ sustains) (NP (NN interest)) (PP (IN during) (NP (NP (DT the) (JJ long) (NN build) (HYPH -) (NN up)) (PP (IN of) (NP (JJ expository) (NN material))))))))
(ROOT (S (VP (VBZ ) (NP (NN )) (PP (IN ) (NP (NP (DT ) (JJ ) (NN ) (HYPH ) (NN )) (PP (IN ) (NP (JJ ) (NN ))))))))