( ( A rocket ) ( ( is ( ( ( pushed forward ) ( by ( ( a ( thrust force ) ) ( as large ) ) ) ) ( as ( ( the force ) ( ( the ( exhaust gas ) ) ( makes ( when ( ( going out ) ( of ( the ( rocket nozzle ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN rocket)) (VP (VBZ is) (VP (VBN pushed) (PRT (RP forward)) (PP (IN by) (NP (NP (DT a) (NN thrust) (NN force)) (ADJP (RB as) (JJ large)))) (PP (IN as) (NP (NP (DT the) (NN force)) (SBAR (S (NP (DT the) (JJ exhaust) (NN gas)) (VP (VBZ makes) (SBAR (WHADVP (WRB when)) (S (VP (VBG going) (PRT (RP out)) (PP (IN of) (NP (DT the) (NN rocket) (NN nozzle))))))))))))) (. .)))
A rocket is pushed forward by a thrust force as large as the force the exhaust gas makes when going out of the rocket nozzle.
(ROOT (S (NP (NNP Thrust)) (VP (VBZ is) (NP (NP (DT the) (NN force)) (VP (VBG pushing) (NP (DT a) (NN rocket))))) (. .)))