( They ( ( ( are ( typical ( of ( ( the ( three ( main types ) ) ) ( of galaxies ) ) ) ) ) ( that ( Hubble classified ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBP are) (ADJP (JJ typical) (PP (IN of) (NP (NP (DT the) (CD three) (JJ main) (NNS types)) (PP (IN of) (NP (NNS galaxies)))))) (SBAR (IN that) (S (NP (NNP Hubble)) (VP (VBD classified))))) (. .)))
They are typical of the three main types of galaxies that Hubble classified.
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD three) (NNS types)) (PP (IN of) (NP (NNS galaxies))))) (. .)))