( ( ( The ( only continent ) ) ( without amphibians ) ) ( ( is Antarctica ) . ) )
(ROOT (S (NP (NP (DT The) (JJ only) (NN continent)) (PP (IN without) (NP (NNS amphibians)))) (VP (VBZ is) (NP (NNP Antarctica))) (. .)))
The only  continent without amphibians is Antarctica.
(ROOT (S (NP (NNP Antarctica)) (VP (VBZ is) (NP (NP (DT the) (JJ only) (NN continent)) (PP (IN without) (NP (NNS amphibians))))) (. .)))