当前的经济环境下，垄断现象比较严重。
当前有哪些主要的垄断现象？[{'character': '当', 'pinyin': 'dang1', 'highest pitch': 10.86, 'lowest pitch': 9.99, 'duration': 0.21, 'prosody hierarchy': 'null'}, {'character': '前', 'pinyin': 'qian2', 'highest pitch': 10.27, 'lowest pitch': 7.75, 'duration': 0.26, 'prosody hierarchy': '#2'}, {'character': '有', 'pinyin': 'iou2', 'highest pitch': 10.42, 'lowest pitch': 8.3, 'duration': 0.2, 'prosody hierarchy': '#1'}, {'character': '哪', 'pinyin': 'na3', 'highest pitch': 10.42, 'lowest pitch': 5.65, 'duration': 0.21, 'prosody hierarchy': 'null'}, {'character': '些', 'pinyin': 'xie1', 'highest pitch': 9.91, 'lowest pitch': 5.98, 'duration': 0.18, 'prosody hierarchy': '#1'}, {'character': '主', 'pinyin': 'zhu3', 'highest pitch': 8.75, 'lowest pitch': 5.49, 'duration': 0.16, 'prosody hierarchy': 'null'}, {'character': '要', 'pinyin': 'iao4', 'highest pitch': 10.07, 'lowest pitch': 5.9, 'duration': 0.2, 'prosody hierarchy': 'null'}, {'character': '的', 'pinyin': 'de5', 'highest pitch': 8.27, 'lowest pitch': 6.87, 'duration': 0.1, 'prosody hierarchy': '#1'}, {'character': '垄', 'pinyin': 'long3', 'highest pitch': 6.87, 'lowest pitch': 4.58, 'duration': 0.21, 'prosody hierarchy': 'null'}, {'character': '断', 'pinyin': 'duan4', 'highest pitch': 7.74, 'lowest pitch': 7.09, 'duration': 0.19, 'prosody hierarchy': '#1'}, {'character': '现', 'pinyin': 'xian4', 'highest pitch': 8.34, 'lowest pitch': 6.77, 'duration': 0.19, 'prosody hierarchy': 'null'}, {'character': '象', 'pinyin': 'xiang4', 'highest pitch': 6.92, 'lowest pitch': 4.99, 'duration': 0.33, 'prosody hierarchy': '#4'}]