( ( If ( one ( ( did not ) work ) ) ) ( , ( another ( might . ) ) ) )
(ROOT (S (SBAR (IN If) (S (NP (PRP one)) (VP (VBD did) (RB not) (VP (VB work))))) (, ,) (NP (DT another)) (VP (MD might)) (. .)))
If one did not work, another might.
(ROOT (S (S (VP (TO To) (VP (VB confirm) (NP (NP (DT the) (NN work)) (PP (IN of) (NP (DT another) (NN scientist))))))) (, ,) (NP (DT a) (NN scientist)) (VP (MD might) (VP (VB replicate) (NP (PRP$ their) (NN work)))) (. .)))