( ( When ( ( ( ( ( ( ( the sun ) , ) ( the earth ) ) , ) and ) ( the moon ) ) ( are ( ( lined up ) ( at ( ( the time ) ( of ( ( ( a ( full moon ) ) or ) ( a ( new moon ) ) ) ) ) ) ) ) ) ) ( , ( ( ( the ( combined ( gravitational pull ) ) ) ( of ( the ( ( sun and ) moon ) ) ) ) ( ( create ( spring tides ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NP (DT the) (NN sun)) (, ,) (NP (DT the) (NN earth)) (, ,) (CC and) (NP (DT the) (NN moon))) (VP (VBP are) (VP (VBN lined) (PRT (RP up)) (PP (IN at) (NP (NP (DT the) (NN time)) (PP (IN of) (NP (NP (DT a) (JJ full) (NN moon)) (CC or) (NP (DT a) (JJ new) (NN moon)))))))))) (, ,) (NP (NP (DT the) (VBN combined) (JJ gravitational) (NN pull)) (PP (IN of) (NP (DT the) (NN sun) (CC and) (NN moon)))) (VP (VBP create) (NP (NN spring) (NNS tides))) (. .)))
When the sun, the earth, and the moon are lined up at the time of a full moon or a new moon, the combined gravitational pull of the sun and moon create spring tides.
(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)))))) (. .)))