( ( of ( a four ) ) ( , ( ( ( ( ( ( one , ) ( ( two ( in ( the triplet ) ) ) register ) ) , ) ( of ( ( ( ( ( ( ( a three ) , ) four ) , ) one ) , ) two ) ) ) ( in ( the quadruplet ) ) ) ( register ; ) ) ) )
(ROOT (S (PP (IN of) (NP (DT a) (CD four))) (, ,) (NP (NP (NP (CD one)) (, ,) (SBAR (WHNP (WHNP (CD two)) (PP (IN in) (NP (DT the) (NN triplet)))) (S (VP (VBP register)))) (, ,)) (PP (IN of) (NP (NNP a) (CD three) (, ,) (CD four) (, ,) (CD one) (, ,) (CD two))) (PP (IN in) (NP (DT the) (NN quadruplet)))) (VP (VBP register)) (: ;)))
of a four, one, two in the triplet register, of a three, four, one, two in the quadruplet register;
(ROOT (S (NP (NP (CD Four) (NNS children)) (VP (VBN born) (PP (IN at) (NP (CD one) (NN birth))))) (VP (VBP are) (VP (VBN called) (NP (NNS quadruplets)))) (. .)))