(S (S (CC But) (S (SBAR (WHADVP (WRB when)) (S (BASENP (DT the) (NN truck)) (VP (VP (VBD came) (PP (TO to) (BASENP (DT a) (NN stop)))) (PP (IN in) (NP (BASENP (NN front)) (PP (IN of) (BASENP (DT a) (NN house)))))))) (COMMA ,) (S (BASENP (NN police)) (VP (VBD saw) (SBAR (IN that) (S (BASENP (PRP it)) (VP (VBD was) (NP (NP (BASENP (DT a) (NN boy)) (PRN (COMMA ,) (NP (BASENP (DT a) (JJ second) (NN grader)) (COMMA ,) (ADJP (RB barely) (ADJP (BASENP (NN 4) (NNS feet)) (JJ tall)))) (COMMA ,))) (PP (IN behind) (BASENP (DT the) (NN wheel))))))))))) (PERIOD .))