( Gravity ( ( is ( causes ( ( a number ) ( of ( forces ( in ( ( the structure ) ( of ( ( ropes and ) posts ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Gravity)) (VP (VBZ is) (VP (VBZ causes) (NP (NP (DT a) (NN number)) (PP (IN of) (NP (NP (NNS forces)) (PP (IN in) (NP (NP (DT the) (NN structure)) (PP (IN of) (NP (NNS ropes) (CC and) (NNS posts)))))))))) (. .)))
Gravity is causes a number of forces in the structure of ropes and posts.
(ROOT (S (NP (NNP Gravity)) (VP (VBZ causes) (S (NP (NNS rocks)) (VP (TO to) (VP (VB roll) (ADVP (RB downhill)))))) (. .)))