( ( When ( ( the ( positively-charged electroscope ) ) ( is touched ) ) ) ( , ( ( its charge ) ( ( becomes ( grounded ( -LRB- ( or ( neutralized -RRB- ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (DT the) (JJ positively-charged) (NN electroscope)) (VP (VBZ is) (VP (VBN touched))))) (, ,) (NP (PRP$ its) (NN charge)) (VP (VBZ becomes) (VP (VBN grounded) (PRN (-LRB- -LRB-) (CC or) (VP (VBN neutralized)) (-RRB- -RRB-)))) (. .)))
When the positively-charged electroscope is touched, its charge becomes grounded (or neutralized).
(ROOT (S (NP (NNP Grounding)) (VP (VBZ is) (SBAR (WHADVP (WRB when)) (S (NP (PRP you)) (VP (VB touch) (NP (DT a) (JJ charged) (NN object)) (PP (TO to) (NP (DT the) (NN earth))))))) (. .)))