( ( Explain ( why ( ( the electroscope ) ( has ( this charge ) ) ) ) ) . )
(ROOT (S (VP (VB Explain) (SBAR (WHADVP (WRB why)) (S (NP (DT the) (NN electroscope)) (VP (VBZ has) (NP (DT this) (NN charge)))))) (. .)))
Explain why the electroscope has this charge.
(ROOT (S (NP (DT A) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN electroscope)) (VP (VBZ is) (VP (VBN used) (S (VP (TO to) (VP (VB study) (NP (NN charge))))))) (. .)))