(S (S (BASENP (DT A) (NNP California) (NN study)) (VP (PRN (COMMA ,) (ADVP (RB however)) (COMMA ,)) (VP (VBD showed) (NP (NN evidence) (SBAR (IN that) (S (PP (IN in) (NP (BASENP (NNS areas)) (SBAR (WHADVP (WRB where)) (S (BASENP (JJ aerial) (NN spraying)) (VP (VBD occurred)))))) (COMMA ,) (S (BASENP (NN infection)) (VP (VBD was) (NP (BASENP (NN six) (NNS times)) (ADJP (ADJP (RBR less) (JJ likely)) (S (VP (TO to) (VP (VB occur)))))))))))))) (PERIOD .))