( ( ( ( ( Groups 13 ) ( -LRB- ( IIIA -RRB- ) ) ) and ) ( 14 ( -LRB- ( IVA -RRB- ) ) ) ) ( ( ( ( have ( no ( unique names ) ) ) but ) ( are ( often ( ( ( called ( the ( boron-aluminum ( and ( carbon-silicon groups ) ) ) ) ) , ) respectively ) ) ) ) . ) )
(ROOT (S (NP (NP (NP (QP (CD Groups) (CD 13))) (PRN (-LRB- -LRB-) (NP (NNP IIIA)) (-RRB- -RRB-))) (CC and) (NP (NP (CD 14)) (PRN (-LRB- -LRB-) (NP (NNP IVA)) (-RRB- -RRB-)))) (VP (VP (VBP have) (NP (DT no) (JJ unique) (NNS names))) (CC but) (VP (VBP are) (VP (ADVP (RB often)) (VBN called) (NP (DT the) (JJ boron-aluminum) (CC and) (JJ carbon-silicon) (NNS groups)) (, ,) (ADVP (RB respectively))))) (. .)))
Groups 13 (IIIA) and 14 (IVA) have no unique names but are often called the boron-aluminum and carbon-silicon groups, respectively.
(ROOT (S (NP (NP (NNP Group) (CD 13)) (PP (IN of) (NP (DT the) (JJ periodic) (NN table)))) (VP (VBZ is) (ADVP (RB also)) (VP (VBN called) (NP (DT the) (DT the) (NN boron) (NN group)))) (. .)))