( ( At ( the ( same time ) ) ) ( , ( ( input units ) ( ( ( are ( recursively ( expanded ( to ( ( their equivalents ) ( in ( terms ( of ( base units ) ) ) ) ) ) ) ) ) ( -LRB- ( ( ( ( ( ( ( length , ) mass ) , ) time ) , ) etc. ) -RRB- ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (DT the) (JJ same) (NN time))) (, ,) (NP (NN input) (NNS units)) (VP (VBP are) (ADJP (RB recursively) (VBN expanded) (PP (TO to) (NP (NP (PRP$ their) (NNS equivalents)) (PP (IN in) (NP (NP (NNS terms)) (PP (IN of) (NP (NN base) (NNS units)))))))) (PRN (-LRB- -LRB-) (NP (NP (NP (NN length)) (, ,) (NP (NN mass))) (, ,) (NP (NN time)) (, ,) (FW etc.)) (-RRB- -RRB-))) (. .)))
At the same time, input units are recursively expanded to their equivalents in terms of base units (length, mass, time, etc.).
(ROOT (S (NP (NP (NNP Time)) (, ,) (NP (NN mass)) (, ,) (NP (NN length)) (, ,) (CC and) (NP (NN temperature))) (VP (VBP are) (VP (VBN considered) (S (VP (TO to) (VP (VB be) (NP (NN base) (NNS units))))))) (. .)))