( ( ( An ( organic compound ) ) ( ( consisting mainly ) ( of ( carbon ( and ( hydrogen atoms ) ) ) ) ) ) ( ( linked ( by ( nonpolar ( covalent bonds ) ) ) ) . ) )
(ROOT (S (NP (NP (DT An) (JJ organic) (NN compound)) (VP (VBG consisting) (ADVP (RB mainly)) (PP (IN of) (NP (NN carbon) (CC and) (NN hydrogen) (NNS atoms))))) (VP (VBN linked) (PP (IN by) (NP (NN nonpolar) (NN covalent) (NNS bonds)))) (. .)))
An organic compound consisting mainly of carbon and hydrogen atoms linked by nonpolar covalent bonds.
(ROOT (S (NP (NN Hydrogen) (NN chloride)) (VP (VBZ is) (NP (DT a) (JJ covalent) (NN compound))) (. .)))