(S (S (BASENP (NNP Chief) (NNP Executive) (NNP Donald) (NNP Tsang)) (VP (VBD called) (PP (IN for) (NP (BASENP (DT an) (NN investigation)) (PP (IN into) (NP (BASENP (DT the) (NN cause)) (PP (IN of) (BASENP (DT the) (NN building) (NN collapse))))))))) (PERIOD .))