(S (S (BASENP (NNS Investigators)) (VP (VBP are) (VP (ADVP (RB also)) (VP (VP (VBG examining) (BASENP (DT the) (NN bus))) (S (VP (TO to) (VP (VB try) (S (VP (TO to) (VP (VB determine) (NP (BASENP (DT any) (NN sign)) (PP (IN of) (BASENP (JJ mechanical) (NN trouble)))))))))))))) (PERIOD .))