( ( ( ( Up and ) down ) ( quarks group ) ) ( together ( in ( ( threes ( to ( produce ( ( protons and ) neutrons ) ) ) ) . ) ) ) )
(ROOT (S (NP (UCP (PP (IN Up)) (CC and) (ADVP (RB down))) (NN quarks) (NN group)) (ADVP (RB together)) (ADVP (RB in)) (VP (VBZ threes) (S (VP (TO to) (VP (VB produce) (NP (NNS protons) (CC and) (NNS neutrons)))))) (. .)))
Up and down quarks group together in threes to produce protons and neutrons.
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD three) (NNS quarks)) (PP (IN in) (NP (DT each) (NN proton) (CC and) (NN neutron))))) (. .)))