( Normally ( ( the ( immune system ) ) ( ( ( fights off ) ( ( infection , ) ( fights ( off cancer ) ) ) ) . ) ) )
(ROOT (S (ADVP (RB Normally)) (NP (DT the) (JJ immune) (NN system)) (VP (VBZ fights) (PRT (RP off)) (NP (NP (NN infection)) (, ,) (NP (NP (NNS fights)) (PP (IN off) (NP (NN cancer)))))) (. .)))
Normally the immune system fights off infection, fights off cancer.
(ROOT (S (NP (DT A) (JJ healthy) (JJ immune) (NN system)) (VP (VBZ fights) (PRT (RP off)) (NP (NP (NNS infections)) (CC and) (NP (JJ other) (NNS dieases)))) (. .)))