( ( ( ( A ( synthesis reaction ) ) or ) ( direct ( combination reaction ) ) ) ( ( is ( ( ( a type ) ( of ( chemical reaction ) ) ) ( ( in which ) ( ( ( ( two or ) more ) ( simple substances ) ) ( combine ( to ( form ( a ( ( more complex ) product ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT A) (NN synthesis) (NN reaction)) (CC or) (NP (JJ direct) (NN combination) (NN reaction))) (VP (VBZ is) (NP (NP (DT a) (NN type)) (PP (IN of) (NP (NN chemical) (NN reaction))) (SBAR (WHPP (IN in) (WHNP (WDT which))) (S (NP (QP (CD two) (CC or) (JJR more)) (JJ simple) (NNS substances)) (VP (VBP combine) (S (VP (TO to) (VP (VB form) (NP (DT a) (ADJP (RBR more) (JJ complex)) (NN product)))))))))) (. .)))
A synthesis reaction or direct combination reaction is a type of chemical reaction in which two or more simple substances combine to form a more complex product.
(ROOT (S (NP (DT A) (NN combination) (NN reaction)) (VP (VBZ is) (NP (NP (DT a) (NN reaction)) (SBAR (WHPP (IN in) (WHNP (WDT which))) (S (NP (CD two) (CC or) (JJR more) (NNS substances)) (VP (VBP combine) (S (VP (TO to) (VP (VB form) (NP (DT a) (JJ single) (JJ new) (NN substance)))))))))) (. .)))