imagine susan sontag falling in love with howard stern . 
(ROOT (S (VP (VB imagine) (S (NP (NNP susan) (NN sontag)) (VP (VBG falling) (PP (IN in) (NP (NN love))) (PP (IN with) (NP (NNP howard) (NN stern)))))) (. .)))
(ROOT (S (VP (VB ) (S (NP (NNP ) (NN )) (VP (VBG ) (PP (IN ) (NP (NN ))) (PP (IN ) (NP (NNP ) (NN )))))) (. )))