( ( ( react , ) ( test ( ( A substance ) ( is ( tested ( for ( ( a reaction ) ( with ( another substance ) ) ) ) ) ) ) ) ) ; )
(ROOT (S (VP (VP (VB react)) (, ,) (VP (VB test) (SBAR (S (NP (DT A) (NN substance)) (VP (VBZ is) (VP (VBN tested) (PP (IN for) (NP (NP (DT a) (NN reaction)) (PP (IN with) (NP (DT another) (NN substance))))))))))) (: ;)))
react, test A substance is tested for a reaction with another substance;
(ROOT (S (NP (NNP Combustion) (NN reaction)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (NN substance)) (VP (VBZ reacts) (ADVP (RB quickly)) (PP (IN with) (NP (NN oxygen))))))) (. .)))