1、晚上12点就是次日的00：00了，所以要用00：00 AM来表示。
2、如果用12：00 PM来表示，那就成了次日的晚上12点了，显然是错误的。
拓展资料
a.m
1、The clock had stopped at 2.12 a.m
钟在凌晨2点12分时停了。
2、Breakfast is available to fishermen from 6 a.m
从早上6点开始向渔民提供早餐。
3、Eve, squinting at the clock, saw it was just on 7 a.m
伊夫眯着眼瞥了一下钟，看到差不多是早上7点钟。
4、Ok, go to bed early because we will set out at6:30 a.m tomorrow.
好了，今天早点休息吧，明天我们早上6点30都出发了。
5、We work from seven a.m to p.m every day.
我们每天从上午七点到晚上十点营业。
p.m
1、The meeting began at precisely 4.00 p.m
会议于下午4点整开始。
2、The area of the President's residence is a no-go area after six p.m
总统官邸区域在下午6点钟后禁止进入。
3、I'll go to see the movie for the3 p.m show.
我将要去看下午3点的那场电影。
4、We work from seven a.m to p.m every day.
我们每天从上午七点到晚上十点营业。
5、It stops incredibly at1:30 P.M Now it is sunny outside, just like the morning of Chinese summer.
可雪下到下午一点半左右，居然停了，走出门一看还开太阳了，就象是中国夏天的早上。