下面这句话中为什么非谓语动词（不定式）做后置定语时，前面还能带个副词短语”most likely”？

Question

The life forms most likely to develop on a planet would be bacteria.（行星上最容易生存下来的是细菌。）——《新概念英语》

Answer 1

这里的most likey不是副词短语 而是形容词最高级 译为最有可能
这句话的主干是The life forms would be bacteria. 而likely后接不定式构成形容词短语，作后置定语。most likely to develop on a planet 相当于一个定语从句省略了关系代词that/which和系动词
原句=The life forms that are most likely to develop on a planet would be bacterial.
likely后接不定式构成形容词短语，作后置定语 例子：
the developments most likely to change...
=the developments which are most likely to change...

Answer 2

不定式就是动词不定式，当然可以被副词修饰。
类似结构:He is old enough to live by himself.