Think of your greatest accomplishments.
( ( Think ( of ( your ( greatest accomplishments ) ) ) ) . )
(ROOT (S (VP (VB Think) (PP (IN of) (NP (PRP$ your) (JJS greatest) (NNS accomplishments)))) (. .)))
What is your greatest accomplishment? 
( What ( ( is ( your ( greatest accomplishment ) ) ) ? ) )
(ROOT (SBARQ (WHNP (WP What)) (SQ (VP (VBZ is) (NP (PRP$ your) (JJS greatest) (NN accomplishment)))) (. ?)))