( ( the ( C-N ( triple bond ) ) ) ( ( contributes ( ( ( one sigma ) and ) ( two ( pi bonds ) ) ) ) . ) )
(ROOT (S (NP (DT the) (JJ C-N) (JJ triple) (NN bond)) (VP (VBZ contributes) (NP (NP (CD one) (NN sigma)) (CC and) (NP (CD two) (NN pi) (NNS bonds)))) (. .)))
the C-N triple bond contributes one sigma and two pi bonds.
(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))))) (. .)))