( ( In ( ( normal forms ) ( of matter ) ) ) ( , ( quarks ( ( are ( ( bound together ) ( by ( ( other particles ) ( ( called gluons ) ( to ( form ( ( ( more complex ) particles ) ( such ( as ( ( protons and ) neutrons ) ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NP (JJ normal) (NNS forms)) (PP (IN of) (NP (NN matter))))) (, ,) (NP (NNS quarks)) (VP (VBP are) (VP (VBN bound) (PRT (RP together)) (PP (IN by) (NP (NP (JJ other) (NNS particles)) (VP (VBN called) (NP (NNS gluons)) (S (VP (TO to) (VP (VB form) (NP (NP (ADJP (RBR more) (JJ complex)) (NNS particles)) (PP (JJ such) (IN as) (NP (NNS protons) (CC and) (NNS neutrons)))))))))))) (. .)))
In normal forms of matter, quarks are bound together by other particles called gluons to form more complex particles such as protons and neutrons.
(ROOT (S (NP (NNS Protons) (CC and) (NNS neutrons)) (VP (VBP are) (VP (VBN made) (PP (IN of) (NP (NP (NNS quarks)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBP are) (NP (NP (JJ fundamental) (NNS particles)) (PP (IN of) (NP (NN matter))))))))))) (. .)))