( ( ( Two years ) later ) ( , ( Mendeleev ( ( ( ( revised ( his table ) ) , ) ( ( ( ( ( placing hydrogen ) ( in ( ( group 1 ) ( above lithium ) ) ) ) , ) and ) ( also ( ( moving thallium ) ( to ( the ( boron group ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (NP (CD Two) (NNS years)) (RB later)) (, ,) (NP (NNP Mendeleev)) (VP (VBD revised) (NP (PRP$ his) (NN table)) (, ,) (S (VP (VP (VBG placing) (NP (NN hydrogen)) (PP (IN in) (NP (NP (NN group) (CD 1)) (PP (IN above) (NP (NN lithium)))))) (, ,) (CC and) (VP (ADVP (RB also)) (VBG moving) (NP (NN thallium)) (PP (TO to) (NP (DT the) (NN boron) (NN group))))))) (. .)))
Two years later, Mendeleev revised his table, placing hydrogen in group 1 above lithium, and also moving thallium to the boron group.
(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)))) (. .)))