(S (S (BASENP (PRP They)) (VP (VBP are) (VP (VBN run) (PP (IN by) (NP (BASENP (NNP Ottobrock)) (COMMA ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ has) (VP (VBN been) (VP (VP (VP (VBG repairing) (BASENP (NNS wheelchairs))) (PP (IN at) (BASENP (DT the) (NNP Paralympics)))) (PP (IN since) (BASENP (NN 1988))))))))))))) (PERIOD .))