( ( When ( ( ( the crests ) ( of ( one wave ) ) ) ( coincide ( with ( ( the crests ) ( of ( another wave ) ) ) ) ) ) ) ( , ( interference ( ( is ( ( ( constructive and ) ( a ( large wave ) ) ) results ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NP (DT the) (NNS crests)) (PP (IN of) (NP (CD one) (NN wave)))) (VP (VB coincide) (PP (IN with) (NP (NP (DT the) (NNS crests)) (PP (IN of) (NP (DT another) (NN wave)))))))) (, ,) (NP (NN interference)) (VP (VBZ is) (NP (UCP (ADJP (JJ constructive)) (CC and) (NP (DT a) (JJ large) (NN wave))) (NNS results))) (. .)))
When the crests of one wave coincide with the crests of another wave, interference is constructive and a large wave results.
(ROOT (S (NP (JJ Constructive) (NN interference)) (VP (VBZ is) (SBAR (WHADVP (WRB when)) (S (NP (CD two) (NNS waves)) (VP (VBP combine) (S (VP (TO to) (VP (VB create) (NP (DT a) (JJR larger) (NN wave))))))))) (. .)))