( ( Your reaction ) ( ( may ( be ( ( positive or ) negative ) ) ) . ) )
(ROOT (S (NP (PRP$ Your) (NN reaction)) (VP (MD may) (VP (VB be) (ADJP (JJ positive) (CC or) (JJ negative)))) (. .)))
Your reaction may be positive or negative.
(ROOT (S (S (VP (VBZ Is) (NP (NP (DT the) (NN heat)) (PP (IN of) (NP (NP (NN reaction)) (PP (IN for) (NP (DT an) (JJ endothermic) (NN reaction)))))))) (VP (VBZ is) (ADJP (JJ positive))) (. .)))