( ( ( ( ( The ( ( most extreme ) tides ) ) , ) ( spring tides ) ) , ) ( ( occur ( when ( ( the ( ( sun and ) moon ) ) ( ( ( are ( lined up ) ) and ) ( act together ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (ADJP (RBS most) (JJ extreme)) (NNS tides)) (, ,) (NP (NN spring) (NNS tides)) (, ,)) (VP (VBP occur) (SBAR (WHADVP (WRB when)) (S (NP (DT the) (NN sun) (CC and) (NN moon)) (VP (VP (VBP are) (VP (VBN lined) (PRT (RP up)))) (CC and) (VP (VBP act) (ADVP (RB together))))))) (. .)))
The most extreme tides, spring tides, occur when the sun and moon are lined up and act together.
(ROOT (S (NP (NNP Spring) (NNS tides)) (VP (VBP are) (VP (VBN created) (SBAR (WHADVP (WRB when)) (S (NP (NP (DT the) (NN sun)) (CC and) (NP (NP (NN moon) (POS 's)) (NNS tides))) (VP (VBP match)))))) (. .)))