( ( At ( this time ) ) ( it ( ( appears ( that ( ( ( the ( two ( basic constituents ) ) ) ( of matter ) ) ( are ( ( ( the ( ( lepton and ) quark ) ) , ) ( ( of ( each ( of which ) ) ) ( there ( are ( believed ( to ( be ( six types ) ) ) ) ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (IN At) (NP (DT this) (NN time))) (NP (PRP it)) (VP (VBZ appears) (SBAR (IN that) (S (NP (NP (DT the) (CD two) (JJ basic) (NNS constituents)) (PP (IN of) (NP (NN matter)))) (VP (VBP are) (NP (NP (DT the) (NN lepton) (CC and) (NN quark)) (, ,) (SBAR (WHPP (IN of) (WHNP (NP (DT each)) (WHPP (IN of) (WHNP (WDT which))))) (S (NP (EX there)) (VP (VBP are) (VP (VBN believed) (S (VP (TO to) (VP (VB be) (NP (CD six) (NNS types)))))))))))))) (. .)))
At this time it appears that the two basic constituents of matter are the lepton and quark, of each of which there are believed to be six types.
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD six) (NNS types)) (PP (IN of) (NP (NNS leptons))))) (. .)))