( ( Ozone gas ) ( ( is ( ( produced ( during ( electric discharge ) ) ) ( by ( ( sparking ( or ( corona discharge ) ) ) ( for example ) ) ) ) ) . ) )
(ROOT (S (NP (NN Ozone) (NN gas)) (VP (VBZ is) (VP (VBN produced) (PP (IN during) (NP (JJ electric) (NN discharge))) (PP (IN by) (NP (NP (NN sparking) (CC or) (NN corona) (NN discharge)) (PP (IN for) (NP (NN example))))))) (. .)))
Ozone gas is produced during electric discharge by sparking or corona discharge for example.
(ROOT (S (NP (NN Ozone)) (VP (VBZ is) (NP (NP (DT a) (NN compound)) (VP (VBN formed) (SBAR (WHADVP (WRB when)) (S (NP (EX there)) (VP (VBZ is) (VP (VBG sparking) (NP (JJ electrical) (NN equipment))))))))) (. .)))