(S (S (BASENP (DT The) (NNS pirates)) (VP (VP (VBD towed) (NP (BASENP (DT a) (NN cannon)) (SBAR (WHNP (WDT which)) (S (BASENP (PRP they)) (VP (VBD fired)))))) (CC and) (VP (VBD shocked) (BASENP (DT the) (NNS crowds))))) (PERIOD .))