( This ( ( was ( followed ( by ( ( a ( loud crash ) ) ( sounding ( like ( an explosion ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBD was) (VP (VBN followed) (PP (IN by) (NP (NP (DT a) (JJ loud) (NN crash)) (VP (VBG sounding) (PP (IN like) (NP (DT an) (NN explosion)))))))) (. .)))
This was followed by a loud crash sounding like an explosion.
(ROOT (S (NP (NP (DT The) (NN sound)) (PP (IN in) (NP (DT a) (JJ loud) (NN classroom)))) (VP (VBZ is) (NP (NP (DT an) (NN example)) (PP (IN of) (NP (NP (DT a) (NN form)) (PP (IN of) (NP (NN energy))))))) (. .)))