Earth to Marvin.
( ( Earth ( to Marvin ) ) . )
(ROOT (NP (NP (NNP Earth)) (PP (TO to) (NP (NNP Marvin))) (. .)))
Marvin, what's going on?
( Marvin ( , ( what ( ( 's ( going on ) ) ? ) ) ) )
(ROOT (SBARQ (NP (NNP Marvin)) (, ,) (WHNP (WP what)) (SQ (VBZ 's) (VP (VBG going) (PRT (RP on)))) (. ?)))