( Volcanoes ( ( are ( ( the ( primary landforms ) ) ( ( ( built ( by ( ( repeated eruptions ) ( of lava ) ) ) ) and ) ( ash ( over time ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Volcanoes)) (VP (VBP are) (NP (NP (DT the) (JJ primary) (NNS landforms)) (VP (VP (VBN built) (PP (IN by) (NP (NP (VBN repeated) (NNS eruptions)) (PP (IN of) (NP (NN lava)))))) (CC and) (VP (ADJP (JJ ash)) (PP (IN over) (NP (NN time))))))) (. .)))
Volcanoes are the primary landforms built by repeated eruptions of lava and ash over time.
(ROOT (S (NP (NP (NNP Ash)) (SBAR (WHNP (WDT that)) (S (VP (VBZ enters) (NP (DT the) (NN air)) (PP (ADVP (RB naturally)) (IN as) (NP (NP (DT a) (NN result)) (PP (IN of) (NP (DT a) (NN volcano) (NN eruption))))))))) (VP (VBZ is) (VP (VBN classified) (PP (IN as) (NP (DT a) (JJ primary) (NN pollutant))))) (. .)))