( ( ( Charge ( the electroscope ) ) ( with ( the ( rubber rod ) ) ) ) . )
(ROOT (S (VP (VB Charge) (NP (DT the) (NN electroscope)) (PP (IN with) (NP (DT the) (NN rubber) (NN rod)))) (. .)))
Charge the electroscope with the rubber rod.
(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))))))) (. .)))