( ( ( ( ( Nuclear fusion ) , ) ( a ( ( very complicated ) process ) ) ) , ) ( ( is ( ( ( what ( makes ( our sun ) ) ) and ) ( ( the rest ) ( of ( the ( stars shine ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Nuclear) (NN fusion)) (, ,) (NP (DT a) (ADJP (RB very) (VBN complicated)) (NN process)) (, ,)) (VP (VBZ is) (NP (NP (SBAR (WHNP (WP what)) (S (VP (VBZ makes) (NP (PRP$ our) (NN sun)))))) (CC and) (NP (NP (DT the) (NN rest)) (PP (IN of) (NP (DT the) (NNS stars) (NN shine)))))) (. .)))
Nuclear fusion, a very complicated process, is what makes our sun and the rest of the stars shine.
(ROOT (S (NP (NP (JJ Nuclear) (NN fusion)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ results) (PP (RB because) (IN of) (NP (NP (JJ great) (NN pressure)) (PP (IN at) (NP (NP (DT the) (NN center)) (PP (IN of) (NP (DT a) (NN star)))))))))) (, ,)) (VP (VBZ causes) (S (NP (NNS stars)) (VP (TO to) (VP (VB shine))))) (. .)))