( You ( ( can ( ( ( use ( your ( own class ) ) ) ( plus ( ( ( seven ( other classes ) ) or ) ( ( two classes ) ( divided ( into ( ( four groups ) each ) ) ) ) ) ) ) ( -LRB- ( ( ( 8 groups ) ( in all ) ) -RRB- ) ) ) ) . ) )
(ROOT (S (NP (PRP You)) (VP (MD can) (VP (VB use) (NP (PRP$ your) (JJ own) (NN class)) (PP (CC plus) (NP (NP (CD seven) (JJ other) (NNS classes)) (CC or) (NP (NP (CD two) (NNS classes)) (VP (VBN divided) (PP (IN into) (NP (NP (CD four) (NNS groups)) (NP (DT each)))))))) (PRN (-LRB- -LRB-) (NP (NP (CD 8) (NNS groups)) (PP (IN in) (NP (DT all)))) (-RRB- -RRB-)))) (. .)))
You can use your own class plus seven other classes or two classes divided into four groups  each (8 groups in all).
(ROOT (S (NP (NNS Mollusks)) (VP (MD can) (VP (VB be) (VP (VBN divided) (PP (IN into) (NP (CD seven) (NNS classes)))))) (. .)))
Mollusks can be divided into seven classes.