( ( triple ( ( -LRB- ( ( ( ( one sigma ) and ) ( two pi ) ) -RRB- ) ) bonds ) ) ( also ( occur . ) ) )
(ROOT (S (NP (JJ triple) (PRN (-LRB- -LRB-) (NP (NP (CD one) (NN sigma)) (CC and) (NP (CD two) (NN pi))) (-RRB- -RRB-)) (NNS bonds)) (ADVP (RB also)) (VP (VBP occur)) (. .)))
triple (one sigma and two pi) bonds also occur.
(ROOT (S (NP (DT A) (JJ double) (NN bond)) (VP (VBZ consists) (PP (IN of) (NP (NP (CD one) (NN sigma) (NN bond)) (CC and) (NP (CD one) (NN pi) (NN bond))))) (. .)))