The thin plastic sheet effectively cuts off the flow of room air through the fabric.
( ( The ( thin ( plastic sheet ) ) ) ( effectively ( ( ( ( cuts off ) ( ( the flow ) ( of ( room air ) ) ) ) ( through ( the fabric ) ) ) . ) ) )
(ROOT (S (NP (DT The) (JJ thin) (JJ plastic) (NN sheet)) (ADVP (RB effectively)) (VP (VBZ cuts) (PRT (RP off)) (NP (NP (DT the) (NN flow)) (PP (IN of) (NP (NN room) (NN air)))) (PP (IN through) (NP (DT the) (NN fabric)))) (. .)))
The sheet of plastic used to control air flow is very thick.
( ( ( The sheet ) ( of ( plastic ( used ( to ( control ( air flow ) ) ) ) ) ) ) ( ( is ( very thick ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN sheet)) (PP (IN of) (NP (NP (NN plastic)) (VP (VBN used) (S (VP (TO to) (VP (VB control) (NP (NN air) (NN flow))))))))) (VP (VBZ is) (ADJP (RB very) (JJ thick))) (. .)))