what may be the performances of their careers 
(ROOT (SBAR (WHNP (WP what)) (S (VP (MD may) (VP (VB be) (NP (NP (DT the) (NNS performances)) (PP (IN of) (NP (PRP$ their) (NNS careers)))))))))
(ROOT (SBAR (WHNP (WP )) (S (VP (MD ) (VP (VB ) (NP (NP (DT ) (NNS )) (PP (IN ) (NP (PRP$ ) (NNS )))))))))