( ( ( Fill ( ( the holes ) ( with water ) ) ) ( until ( ( the water ) ( bubbles ( to ( the top ) ) ) ) ) ) . )
(ROOT (S (VP (VB Fill) (NP (NP (DT the) (NNS holes)) (PP (IN with) (NP (NN water)))) (SBAR (IN until) (S (NP (DT the) (NN water)) (VP (VBZ bubbles) (PP (TO to) (NP (DT the) (NN top))))))) (. .)))
Fill the holes with water until the water bubbles to the top.
(ROOT (S (NP (NNP Gas) (NN bubble) (NNS holes)) (VP (VBZ helps) (NP (NP (JJ pumice) (NN float)) (PP (IN in) (NP (NN water))))) (. .)))