are rolling over in their graves 
(ROOT (S (VP (VBP are) (VP (VBG rolling) (PRT (RP over)) (PP (IN in) (NP (PRP$ their) (NNS graves)))))))
(ROOT (S (VP (VBP ) (VP (VBG ) (PRT (RP )) (PP (IN ) (NP (PRP$ ) (NNS )))))))