(S (S (NP (BASENP (JJ Several) (NNS others)) (PP (IN with) (BASENP (DT the) (NN virus)))) (VP (VP (VBP have) (VP (VBN shown) (BASENP (JJ few) (NNS symptoms)))) (CC or) (VP (VBP are) (PP (IN in) (BASENP (DT a) (JJ stable) (NN condition)))))) (PERIOD .))