( ( Area graphs ) ( ( are ( used ( to ( ( ( ( show ( how ( something ( changes ( over time ) ) ) ) ) , ) and ) ( have ( ( ( ( an x-axis ) ( -LRB- ( horizontal -RRB- ) ) ) and ) ( ( a y-axis ) ( -LRB- ( vertical -RRB- ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Area) (NNS graphs)) (VP (VBP are) (VP (VBN used) (S (VP (TO to) (VP (VP (VB show) (SBAR (WHADVP (WRB how)) (S (NP (NN something)) (VP (VBZ changes) (PP (IN over) (NP (NN time))))))) (, ,) (CC and) (VP (VB have) (NP (NP (NP (DT an) (NNS x-axis)) (PRN (-LRB- -LRB-) (ADJP (JJ horizontal)) (-RRB- -RRB-))) (CC and) (NP (NP (DT a) (NNS y-axis)) (PRN (-LRB- -LRB-) (NP (NNP vertical)) (-RRB- -RRB-)))))))))) (. .)))
Area graphs are used to show how something changes over time, and have an x-axis (horizontal) and a y-axis (vertical).
(ROOT (S (NP (NNP Line) (NNS graphs)) (VP (VBP are) (ADJP (RB especially) (JJ useful) (PP (IN for) (S (VP (VBG showing) (NP (NNS changes)) (PP (IN over) (NP (NN time)))))))) (. .)))