( ( ( Note also ) ( that ( anions ( ( ( can ( have ( ( more ( than one ) ) ( negative charge ) ) ) ) and ) ( may ( be ( combinations ( of ( elements ( with oxygen ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (VP (NN Note) (ADVP (RB also)) (SBAR (IN that) (S (NP (NNS anions)) (VP (VP (MD can) (VP (VB have) (NP (QP (JJR more) (IN than) (CD one)) (JJ negative) (NN charge)))) (CC and) (VP (MD may) (VP (VB be) (NP (NP (NNS combinations)) (PP (IN of) (NP (NP (NNS elements)) (PP (IN with) (NP (NN oxygen)))))))))))) (. .)))
Note also that anions can have more than one negative charge and may be combinations of elements with oxygen.
(ROOT (S (NP (DT A) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN anion)) (VP (VBZ is) (VP (VBN formed) (SBAR (WHADVP (WRB when)) (S (NP (DT an) (NN element)) (VP (VBZ gains) (NP (QP (CD one) (CC or) (JJR more)) (NNS electrons))))))) (. .)))