( ( Most precipitation ) ( ( comes ( in ( the summer ) ) ) . ) )
(ROOT (S (NP (JJS Most) (NNS precipitation)) (VP (VBZ comes) (PP (IN in) (NP (DT the) (NN summer)))) (. .)))
Most precipitation comes in the summer.
(ROOT (S (NP (NNP Groundwater)) (ADVP (RB primarily)) (VP (VBZ comes) (PP (IN from) (NP (NN precipitation)))) (. .)))