a rumor of angels should dispel it . 
(ROOT (S (NP (NP (DT a) (NN rumor)) (PP (IN of) (NP (NNS angels)))) (VP (MD should) (VP (VB dispel) (NP (PRP it)))) (. .)))
(ROOT (S (NP (NP (DT ) (NN )) (PP (IN ) (NP (NNS )))) (VP (MD ) (VP (VB ) (NP (PRP )))) (. )))