One day, a teacher was giving a speech to his students .He held up（举起）a glass of water and asked the class. "How heavy do you think this glass of water is ?"
   The students’ answers ranged（范围） from 20g to 500g .
   "It does not matter on the weight itself .It depends on how long you hold it .If I hold it for a minute ,it is OK. If I hold it for an hour ,I will have an ache in my right arm .If I hold it for a day ,you will have to call an ambulance（救护车）.It is exactly the same weight ,but the longer I hold it ,the heavier it becomes."
   "If we carry our burdens （负担）all the time, sooner or later ,we will not be able to carry on ,the burden becoming increasingly heavier ."
"What you have to do is to put the glass down ,rest for a while before holding it up again ."
   We have to put down the burden sometimes ,so that we can be refreshed and are able to carry on .
   So before you return home from work tonight ,put the burden of work down .Don’t carry it back home. You can pick it up tomorrow .
Whatever burdens you are having now on your shoulders, let it down for a moment if you can .

若函数$y=\cos \left(\omega x+\frac{\pi }{6}\right)\left(\omega \in N^{*}\right)$的一个对称中心是$\left(\frac{\pi }{6},0\right)$，则$\omega$的最小值为（   ）

一位学者研究了十一大（1977）至十五大（1997）五个大会报告中的关键词汇的变迁，其中四个报告中的词汇使用有如下特点，按照时间先后排序正确的是（    ）

①“市场经济”成为报告的新词汇

②“改革”“对外开放”第一次出现在报告中

③报告中“毛主席”一词平均每个自然段提及两次

④报告中“初级阶段的基本路线”成为高频词汇

按照《汉语拼音字母表》的顺序排列下面的字母，并写出对应的小写字母。

H J Y M N D R P C V

大写排序：____

对应小写：____