( Ozone ( ( is ( formed ( when ( ( an ( electric spark ) ) ( ( ( ( is ( passed ( through oxygen ) ) ) , ) and ) ( causes ( ( a ( detectable odor ) ) ( near ( electrical machinery ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NN Ozone)) (VP (VBZ is) (VP (VBN formed) (SBAR (WHADVP (WRB when)) (S (NP (DT an) (JJ electric) (NN spark)) (VP (VP (VBZ is) (VP (VBN passed) (PP (IN through) (NP (NN oxygen))))) (, ,) (CC and) (VP (VBZ causes) (NP (NP (DT a) (JJ detectable) (NN odor)) (PP (IN near) (NP (JJ electrical) (NN machinery)))))))))) (. .)))
Ozone is formed when an electric spark is passed through oxygen, and causes a detectable odor near electrical machinery.
(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))))))))) (. .)))