( ( Persons ( who ( have ( negative tests ) ) ) ) ( ( should ( understand ( that ( ( the ( negative ( test result ) ) ) ( ( does not ) ( ( signify protection ) ( from ( acquiring infection ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Persons)) (SBAR (WHNP (WP who)) (S (VP (VBP have) (NP (JJ negative) (NNS tests)))))) (VP (MD should) (VP (VB understand) (SBAR (IN that) (S (NP (DT the) (JJ negative) (NN test) (NN result)) (VP (VBZ does) (RB not) (VP (VB signify) (NP (NN protection)) (PP (IN from) (S (VP (VBG acquiring) (NP (NN infection))))))))))) (. .)))
Persons who have negative tests should understand that the negative test result does not signify protection from acquiring infection.
(ROOT (S (NP (PRP We)) (VP (VBP call) (NP (NP (DT an) (JJ incorrect) (NN test) (NN result)) (SBAR (WHNP (WDT that)) (S (VP (MD should) (VP (VB have) (VP (VBN been) (ADJP (JJ positive) (NP (NP (DT a) (-LRB- -LRB-) (NN n) (-RRB- -RRB-)) (ADJP (JJ false) (JJ negative))))))))))) (. .)))