最高级可以限于一个事物，也可以用于多个事物。所以用基数词或序数词修饰很正常。以下例句都表明，最高级可以包含多个事物：

I've long thought of it as one of the most beautiful cities in China.  我长期以来都认为它是中国最美的城市之一。

The Yellow River is the second longest river in China. 黄河是中国第二大河。

The four most common  purposes of speech are to inform, to convince, to move to action, and to entertain. ——本句若不用做高级，那么，“最”的意思就无法表达出来了。