奶粉的保质期是多久？
保质期显示在奶粉罐底部。[{'character': '保', 'pinyin': 'bao3', 'highest pitch': 8.08, 'lowest pitch': 6.7, 'duration': 0.19, 'prosody hierarchy': 'null'}, {'character': '质', 'pinyin': 'zhiii4', 'highest pitch': 8.93, 'lowest pitch': 6.7, 'duration': 0.16, 'prosody hierarchy': 'null'}, {'character': '期', 'pinyin': 'qi1', 'highest pitch': 10.3, 'lowest pitch': 7.72, 'duration': 0.27, 'prosody hierarchy': '#2'}, {'character': '显', 'pinyin': 'xian3', 'highest pitch': 9.98, 'lowest pitch': 5.95, 'duration': 0.23, 'prosody hierarchy': 'null'}, {'character': '示', 'pinyin': 'shiii4', 'highest pitch': 8.05, 'lowest pitch': 6.28, 'duration': 0.17, 'prosody hierarchy': 'null'}, {'character': '在', 'pinyin': 'zai4', 'highest pitch': 8.29, 'lowest pitch': 6.62, 'duration': 0.13, 'prosody hierarchy': '#1'}, {'character': '奶', 'pinyin': 'nai2', 'highest pitch': 10.13, 'lowest pitch': 6.42, 'duration': 0.21, 'prosody hierarchy': 'null'}, {'character': '粉', 'pinyin': 'fen3', 'highest pitch': 10.13, 'lowest pitch': 6.41, 'duration': 0.19, 'prosody hierarchy': 'null'}, {'character': '罐', 'pinyin': 'guan4', 'highest pitch': 9.06, 'lowest pitch': 6.63, 'duration': 0.19, 'prosody hierarchy': '#1'}, {'character': '底', 'pinyin': 'di3', 'highest pitch': 7.47, 'lowest pitch': 4.63, 'duration': 0.22, 'prosody hierarchy': 'null'}, {'character': '部', 'pinyin': 'bu4', 'highest pitch': 9.09, 'lowest pitch': 6.65, 'duration': 0.28, 'prosody hierarchy': '#4'}]