i can believe i can believe that
( i ( can ( believe ( i ( can ( believe that ) ) ) ) ) )
(ROOT (S (NP (FW i)) (VP (MD can) (VP (VB believe) (SBAR (S (NP (FW i)) (VP (MD can) (VP (VB believe) (NP (DT that))))))))))
That's something that's believable.
( That ( ( 's ( something ( that ( 's believable ) ) ) ) . ) )
(ROOT (S (NP (DT That)) (VP (VBZ 's) (NP (NP (NN something)) (SBAR (WHNP (WDT that)) (S (VP (VBZ 's) (ADJP (JJ believable))))))) (. .)))