(S (S (SBAR (IN While) (S (VP (VBG driving) (NP (BASENP (PRPD his) (NN bar) (NN stool)) (COMMA ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (VP (VBN powered) (PP (IN by) (BASENP (DT a) (NN lawnmower) (NN engine))))))))))) (COMMA ,) (S (S (S (BASENP (NNP Wygle)) (VP (VBD attempted) (S (VP (TO to) (VP (VB make) (BASENP (DT a) (NN U-turn))))))) (SBAR (IN while) (S (VP (VP (VBG going) (PRT (RP down))) (BASENP (PRPD his) (NN street)))))) (CC and) (S (VP (VBD crashed))))) (PERIOD .))