So, if you want to estimate

如果你想估计一下
how many grammatical sentences

用二十个英文单词
under twenty words in English,

可以组成多少个符合语法的句子
the answer is, "A lot."

答案会是 "很多"
And what this means is

这也就意味着
that any theory of language use and language comprehension

任何语言使用和语言理解的理论
cannot simply appeal to a list.

都无法列出一份句子的清单
When you understand a sentence I said

当你在理解我所说的一句话时
you have to have the capacity to understand a sentence

你必须要拥有理解这句话的能力
even if you've never heard it before.

即使你在之前从未听到过这句话
And this is because we could effortlessly produce and understand sentences

这是因为我们可以毫不费力地创造和理解
that no human has ever said before on earth.

那些世上从未有人说过的句子