( ( ( ( ( ( The ( two ( most ( critical properties ) ) ) ) ( of superconductors ) ) , ) ( ( indeed ( the ( necessary conditions ) ) ) ( for ( establishing ( that ( superconductivity ( exists ( in ( a material ) ) ) ) ) ) ) ) ) , ) ( ( are ( ( ( zero resistance ) and ) ( the ( Meissner effect ) ) ) ) . ) )
(ROOT (S (NP (NP (NP (DT The) (CD two) (JJS most) (JJ critical) (NNS properties)) (PP (IN of) (NP (NNS superconductors)))) (, ,) (NP (NP (RB indeed) (DT the) (JJ necessary) (NNS conditions)) (PP (IN for) (S (VP (VBG establishing) (SBAR (IN that) (S (NP (NN superconductivity)) (VP (VBZ exists) (PP (IN in) (NP (DT a) (NN material)))))))))) (, ,)) (VP (VBP are) (NP (NP (CD zero) (NN resistance)) (CC and) (NP (DT the) (NNP Meissner) (NN effect)))) (. .)))
The two most critical properties of superconductors, indeed the necessary conditions for establishing that superconductivity exists in a material, are zero resistance and the Meissner effect .
(ROOT (S (NP (NNS Superconductors)) (VP (VBP are) (NP (NP (NNS materials)) (PP (IN with) (NP (NP (DT a) (NN resistivity)) (PP (IN of) (NP (CD zero))))))) (. .)))