( ( ( A volcano ) ( on ( the ( planet Venus ) ) ) ) ( ( is ( named ( after Sif ) ) ) . ) )
(ROOT (S (NP (NP (DT A) (NN volcano)) (PP (IN on) (NP (DT the) (NN planet) (NNP Venus)))) (VP (VBZ is) (VP (VBN named) (PP (IN after) (NP (NNP Sif))))) (. .)))
A volcano on the planet Venus is named after Sif.
(ROOT (S (NP (NNP Venus)) (VP (VBZ has) (NP (DT the) (JJS most) (NNS volcanoes))) (. .)))