媒体报道称，有关港铁的出事原因是什么？
港铁至今未交代出事原因。[{'character': '港', 'pinyin': 'gang2', 'highest pitch': 11.29, 'lowest pitch': 7.73, 'duration': 0.26, 'prosody hierarchy': 'null'}, {'character': '铁', 'pinyin': 'tie3', 'highest pitch': 11.29, 'lowest pitch': 5.52, 'duration': 0.29, 'prosody hierarchy': '#2'}, {'pinyin': 'sp1', 'highest pitch': 0.0, 'lowest pitch': 0.0, 'duration': 0.04}, {'character': '至', 'pinyin': 'zhiii4', 'highest pitch': 8.6, 'lowest pitch': 6.68, 'duration': 0.18, 'prosody hierarchy': 'null'}, {'character': '今', 'pinyin': 'jin1', 'highest pitch': 8.54, 'lowest pitch': 6.68, 'duration': 0.17, 'prosody hierarchy': '#1'}, {'character': '未', 'pinyin': 'uei4', 'highest pitch': 8.61, 'lowest pitch': 6.73, 'duration': 0.17, 'prosody hierarchy': 'null'}, {'character': '交', 'pinyin': 'jiao1', 'highest pitch': 8.98, 'lowest pitch': 6.73, 'duration': 0.21, 'prosody hierarchy': 'null'}, {'character': '代', 'pinyin': 'dai4', 'highest pitch': 9.21, 'lowest pitch': 6.93, 'duration': 0.18, 'prosody hierarchy': '#1'}, {'character': '出', 'pinyin': 'chu1', 'highest pitch': 10.26, 'lowest pitch': 6.93, 'duration': 0.21, 'prosody hierarchy': 'null'}, {'character': '事', 'pinyin': 'shiii4', 'highest pitch': 10.23, 'lowest pitch': 7.91, 'duration': 0.16, 'prosody hierarchy': '#1'}, {'character': '原', 'pinyin': 'van2', 'highest pitch': 7.91, 'lowest pitch': 6.09, 'duration': 0.21, 'prosody hierarchy': 'null'}, {'character': '因', 'pinyin': 'in1', 'highest pitch': 9.84, 'lowest pitch': 7.04, 'duration': 0.34, 'prosody hierarchy': '#4'}]