求教less/more作形容词还是副词的问题！附prep原句

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More than 300 rivers drain into Siberia's Lake Baikal, which holds 20 percent of the world's fresh water, more than all the North American Great Lakes combined.

这个是正确答案 prep笔记里解释的是”more than。。。。作为20 percent of .......的同位语“

Employment costs rose 2.8 percent in the 12 months that ended in September, slightly less than they did in the year that ended in the previous quarter.

关于这里的less prep笔记的解释是”less 作副词 修饰rose“

我想知道 这两道题的less/more用法是不是一样？ 这种以less/more开头的分句到底起的什么作用？请赐教！

帮顶

关于第2句:一个说法供参考

我不是很同意笔记说的less做rose的状语, 我认为是做2.8 percent 的同位语,

不过既然2.8 percent 是做rose的状语, 那么 笔记的说法也没错, 别把你给绕晕了