( ( ( An example ) ( of ( ( this type ) ( of crystal ) ) ) ) ( ( is ( ( sodium chloride ) ( -LRB- ( NaCl -RRB- ) ) ) ) . ) )
(ROOT (S (NP (NP (DT An) (NN example)) (PP (IN of) (NP (NP (DT this) (NN type)) (PP (IN of) (NP (NN crystal)))))) (VP (VBZ is) (NP (NP (NN sodium) (NN chloride)) (PRN (-LRB- -LRB-) (NP (NNP NaCl)) (-RRB- -RRB-)))) (. .)))
An example of this type of crystal is sodium chloride (NaCl).
(ROOT (S (NP (NP (NNS Compounds)) (PP (IN like) (NP (NN sodium) (NN chloride) (NN form) (NNS structures)))) (VP (VBD called) (NP (NNS crystals))) (. .)))