( Reaction ( ( ( ( ( was , ) ( as before ) ) , ) ( both ( ( positive and ) negative ) ) ) . ) )
(ROOT (S (NP (NNP Reaction)) (VP (VBD was) (, ,) (ADVP (RB as) (RB before)) (, ,) (ADJP (DT both) (JJ positive) (CC and) (JJ negative))) (. .)))
Reaction was, as before, both positive and 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))) (. .)))