( carbon-hydrogen ( ( covalent bonds ) . ) )
(ROOT (S (NP (NN carbon-hydrogen)) (VP (VBP covalent) (NP (NNS bonds))) (. .)))
carbon-hydrogen covalent bonds.
(ROOT (S (NP (NN Hydrogen) (NN chloride)) (VP (VBZ is) (NP (DT a) (JJ covalent) (NN compound))) (. .)))