( ( ( Demonstrate ( an understanding ) ) ( that ( ( ( two ( fundamental forces ) ) ( acting ( in ( the ( Earth System ) ) ) ) ) ( are ( ( gravity and ) electromagnetism ) ) ) ) ) . )
(ROOT (S (VP (VB Demonstrate) (NP (DT an) (NN understanding)) (SBAR (IN that) (S (NP (NP (CD two) (JJ fundamental) (NNS forces)) (VP (VBG acting) (PP (IN in) (NP (DT the) (NNP Earth) (NNP System))))) (VP (VBP are) (NP (NN gravity) (CC and) (NN electromagnetism)))))) (. .)))
Demonstrate an understanding that two fundamental forces acting in the Earth System are gravity and electromagnetism.
(ROOT (S (NP (NP (NNS Objects)) (PP (IN on) (NP (NN earth)))) (VP (VBP have) (NP (NP (CD two) (NNS forces)) (VP (VBG acting) (PP (IN on) (NP (PRP them))) (PP (IN at) (NP (DT all) (NNS times)))))) (. .)))