( There ( ( are ( ( biodestructive mechanisms ) ( that ( have ( to ( be ( activated ( ( ( ( when ( they ( meet ( ( antigen-antibody complexes ) ( of ( the ( ( ( three or ) ( more different ) ) ( antibody type ) ) ) ) ) ) ) ) , ) ( but not ) ) ( when ( they ( ( meet ( antigen-antibody complexes ) ) ( with ( ( ( only one ) or ) ( two ( different antibodies ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (JJ biodestructive) (NNS mechanisms)) (SBAR (WHNP (WDT that)) (S (VP (VBP have) (S (VP (TO to) (VP (VB be) (VP (VBN activated) (SBAR (SBAR (WHADVP (WRB when)) (S (NP (PRP they)) (VP (VBP meet) (NP (NP (JJ antigen-antibody) (NNS complexes)) (PP (IN of) (NP (DT the) (UCP (NP (CD three)) (CC or) (ADJP (RBR more) (JJ different))) (NN antibody) (NN type))))))) (, ,) (CONJP (CC but) (RB not)) (SBAR (WHADVP (WRB when)) (S (NP (PRP they)) (VP (VB meet) (NP (JJ antigen-antibody) (NNS complexes)) (PP (IN with) (NP (NP (RB only) (CD one)) (CC or) (NP (CD two) (JJ different) (NNS antibodies))))))))))))))))) (. .)))
There are biodestructive mechanisms that have to be activated when they meet antigen-antibody complexes of the three or more different antibody type, but not when they meet antigen-antibody complexes with only one or two different antibodies.
(ROOT (S (NP (DT An) (NN antibody)) (VP (MD can) (VP (VB match) (NP (NP (CD one) (NNS types)) (PP (IN of) (NP (NNS antigens)))))) (. .)))