( Scientists ( ( are ( working ( on it ) ) ) . ) )
(ROOT (S (NP (NNS Scientists)) (VP (VBP are) (VP (VBG working) (PP (IN on) (NP (PRP it))))) (. .)))
Scientists are working on it.
(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)))) (. .)))