there 's a reason why halftime is only fifteen minutes long . 
(ROOT (S (NP (EX there)) (VP (VBZ 's) (NP (NP (DT a) (NN reason)) (SBAR (WHADVP (WRB why)) (S (NP (NN halftime)) (VP (VBZ is) (ADJP (NP (QP (RB only) (CD fifteen)) (NNS minutes)) (JJ long))))))) (. .)))
(ROOT (S (NP (EX )) (VP (VBZ ) (NP (NP (DT ) (NN )) (SBAR (WHADVP (WRB )) (S (NP (NN )) (VP (VBZ ) (ADJP (NP (QP (RB ) (CD )) (NNS )) (JJ ))))))) (. )))