, what an idea , what a thrill ride . 
(ROOT (FRAG (, ,) (WHNP (WDT what) (DT an) (NN idea)) (, ,) (SBAR (WHNP (WP what)) (FRAG (NP (DT a) (NN thrill) (NN ride)))) (. .)))
(ROOT (FRAG (, ) (WHNP (WDT ) (DT ) (NN )) (, ) (SBAR (WHNP (WP )) (FRAG (NP (DT ) (NN ) (NN )))) (. )))