( ( When ( ( the Universe ) ( cools sufficiently ) ) ) ( , ( ( ( ( a ( single electron ) ) and ) proton ) ( ( can ( join ( to ( ( create ( ( ( ( hydrogen , ) ( the simplest ) ) and ) ( ( most abundant ) element ) ) ) ( in ( the Universe ) ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (DT the) (NNP Universe)) (VP (VBZ cools) (ADJP (JJ sufficiently))))) (, ,) (NP (NP (DT a) (JJ single) (NN electron)) (CC and) (NP (NN proton))) (VP (MD can) (VP (VB join) (S (VP (TO to) (VP (VB create) (NP (NP (NN hydrogen)) (, ,) (NP (DT the) (JJS simplest)) (CC and) (NP (ADJP (RBS most) (JJ abundant)) (NN element))) (PP (IN in) (NP (DT the) (NNP Universe)))))))) (. .)))
When the Universe cools sufficiently, a single electron and proton can join to create hydrogen, the simplest and most abundant element in the Universe.
(ROOT (S (NP (NNP Hydrogen)) (VP (VBZ is) (NP (NP (DT the) (ADJP (RBS most) (JJ abundant)) (NN element)) (PP (IN in) (NP (DT the) (NN universe))))) (. .)))