( ( These tides ) ( ( are ( referred ( to ( ( as SPRING ) TIDES ) ) ) ) . ) )
(ROOT (S (NP (DT These) (NNS tides)) (VP (VBP are) (VP (VBN referred) (PP (TO to) (NP (QP (RB as) (CD SPRING)) (NNS TIDES))))) (. .)))
These tides are referred to as 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)))))) (. .)))