( ( ( ( Shield volcanoes ) and ) ( volcanic vents ) ) ( ( have ( been ( found ( on ( Mars ( , ( Venus ( , ( and Io ) ) ) ) ) ) ) ) ) ; ) )
(ROOT (S (NP (NP (NNP Shield) (NNP volcanoes)) (CC and) (NP (JJ volcanic) (NNS vents))) (VP (VBP have) (VP (VBN been) (VP (VBN found) (PP (IN on) (NP (NNP Mars) (, ,) (NNP Venus) (, ,) (CC and) (NNP Io)))))) (: ;)))
Shield volcanoes and volcanic vents have been found on Mars, Venus, and Io;
(ROOT (S (NP (NNP Venus)) (VP (VBZ has) (NP (DT the) (JJS most) (NNS volcanoes))) (. .)))