positive: "12PM 是中午<br>记得我刚来美国的时候,有门课程12PM开始。当时我问教授怎么晚上那么晚了还上课。他笑着说12PM是中午。<br>其实,中国人中分不清楚12AM和12PM的大有人在。我相信很多人把12AM当成是中午,12PM当成晚上。就168肯定就有很多人分不清楚。<br>规则参看:钱多多选股大赛规则截止日期: 11/15/2009 12:00am EST.<br>报名截止。<br>所以我在规则里面,尽量不用12,都用11:59啥的。<br>Are noon and midnight 12 a.m. or 12 p.m.?<br>This is a tricky question. The answer is that the terms 12 a.m. and 12 p.m. are wrong and should not be used.<br>To illustrate this, consider that ""a.m"" and ""p.m."" are abbreviations for ""ante meridiem"" and ""post meridiem."" They mean ""before noon"" and ""after noon,"" respectively. Noon is neither before or after noon; it is simply noon. Therefore, neither the ""a.m."" nor ""p.m."" designation is correct. On the other hand, midnight is both 12 hours before noon and 12 hours after noon. Therefore, either 12 a.m. or 12 p.m. could work as a designation for midnight, but both would be ambiguous as to the date intended.<br>When a specific date is important, and when we can use a 24-hour clock, we prefer to designate that moment not"
negative: 下午两点是未时,未时是从13时至15时,此时太阳蹉跌而下,开始偏西,故又谓之日侧、日映。午后时间,正是人们小息纳凉休闲时刻。因为这个时间段也是人一天中,最为舒适的时间。十二时辰<br>古代将一昼夜分为十二时辰,即:子、丑、寅、卯、辰、巳、午、未、申、酉、戌、亥。每一时辰相当于现代的两个小时。古人根据中国十二生肖中的动物的出没时间来命名各个时辰。子时23~1点,丑时1~3点,寅时3~5点,卯时5~7点,辰时7~9点,巳时9~11点,午时11~13点,未时13~15点,申时15~17点,酉时17~19点,戌时19~21点,亥时21~23点。<br>十二时辰制。西周时就已使用。汉代命名为夜半、鸡鸣、平旦、日出、食时、隅中、日中、日昳、晡时、日入、黄昏、人定。又用十二地支来表示,以夜半二十三点至一点为子时,一至三点为丑时,三至五点为寅时,依次递推。<br>十二时辰是古人根据一日间太阳出没的自然规律、天色的变化以及自己日常的生产活动、生活习惯而归纳总结、独创于世的。十二时表时独特、历史悠久,是中华民族对人类天文历法的一大杰出贡献,也是我国灿烂的文化瑰宝之一。