( ( ( Bubbles and ) Twidledomb ) ( ( ( ( are dead ) and ) ( are ( floating ( on ( top ( of ( the water ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Bubbles) (CC and) (NNP Twidledomb)) (VP (VP (VBP are) (ADJP (JJ dead))) (CC and) (VP (VBP are) (VP (VBG floating) (PP (IN on) (NP (NP (NN top)) (PP (IN of) (NP (DT the) (NN water)))))))) (. .)))
Bubbles and Twidledomb are dead and are floating on top of the water.
(ROOT (S (NP (NNP Gas) (NN bubble) (NNS holes)) (VP (VBZ helps) (NP (NP (JJ pumice) (NN float)) (PP (IN in) (NP (NN water))))) (. .)))