As he stepped across the threshold, Tommy brought the picture down with terrific force on his head.
( ( As ( he ( stepped ( across ( the threshold ) ) ) ) ) ( , ( Tommy ( ( ( brought ( ( ( the picture ) down ) ( with ( terrific force ) ) ) ) ( on ( his head ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN As) (S (NP (PRP he)) (VP (VBD stepped) (PP (IN across) (NP (DT the) (NN threshold)))))) (, ,) (NP (NNP Tommy)) (VP (VBD brought) (PP (ADVP (NP (DT the) (NN picture)) (RB down)) (IN with) (NP (JJ terrific) (NN force))) (PP (IN on) (NP (PRP$ his) (NN head)))) (. .)))
Tommy lightly put the picture on his head.
( Tommy ( lightly ( ( ( put ( the picture ) ) ( on ( his head ) ) ) . ) ) )
(ROOT (S (NP (NNP Tommy)) (ADVP (RB lightly)) (VP (VBD put) (NP (DT the) (NN picture)) (PP (IN on) (NP (PRP$ his) (NN head)))) (. .)))