这是为什么呢？
瓦尔克没有说明诉讼动机。[{'character': '瓦', 'pinyin': 'ua2', 'highest pitch': 11.04, 'lowest pitch': 8.88, 'duration': 0.19, 'prosody hierarchy': 'null'}, {'character': '尔', 'pinyin': 'er3', 'highest pitch': 10.9, 'lowest pitch': 7.17, 'duration': 0.12, 'prosody hierarchy': 'null'}, {'character': '克', 'pinyin': 'ke4', 'highest pitch': 10.1, 'lowest pitch': 7.21, 'duration': 0.3, 'prosody hierarchy': '#2'}, {'character': '没', 'pinyin': 'mei2', 'highest pitch': 9.38, 'lowest pitch': 7.04, 'duration': 0.19, 'prosody hierarchy': 'null'}, {'character': '有', 'pinyin': 'iou3', 'highest pitch': 11.12, 'lowest pitch': 7.46, 'duration': 0.19, 'prosody hierarchy': '#1'}, {'character': '说', 'pinyin': 'shuo1', 'highest pitch': 8.11, 'lowest pitch': 7.41, 'duration': 0.2, 'prosody hierarchy': 'null'}, {'character': '明', 'pinyin': 'ming2', 'highest pitch': 7.51, 'lowest pitch': 6.0, 'duration': 0.23, 'prosody hierarchy': '#1'}, {'character': '诉', 'pinyin': 'su4', 'highest pitch': 7.98, 'lowest pitch': 6.63, 'duration': 0.15, 'prosody hierarchy': 'null'}, {'character': '讼', 'pinyin': 'song4', 'highest pitch': 7.71, 'lowest pitch': 6.8, 'duration': 0.18, 'prosody hierarchy': '#1'}, {'character': '动', 'pinyin': 'dong4', 'highest pitch': 8.3, 'lowest pitch': 5.91, 'duration': 0.19, 'prosody hierarchy': 'null'}, {'character': '机', 'pinyin': 'ji1', 'highest pitch': 8.02, 'lowest pitch': 5.91, 'duration': 0.28, 'prosody hierarchy': '#4'}]