regex - 正则表达式提取一个单词频率只有两次的句子？

Question

aardvark is an animal with aardvark
aardvark is an animal with aardvark along with another aardvark
aardvark is an animal with an elephant that loves an aardvark that lives in downtown

或

aardvark is an animal with aardvark. aardvark is an animal with aardvark along with another aardvark. aardvark is an animal with an elephant that loves an aardvark that lives in downtown

这是我必须只提取 aardvark 只出现两次的句子的文本。

我试过这个表达式 ((.*?)(aardvark)(.*?)(aardvark)(.*?)[\.\n]) 和 (.*\baardvark\b.*){2} 但我得到的所有句子都是答案。

我该如何处理？

Answer 1

试试这个:

^(((?!\baardvark\b)\b\w+\b\s+)*?\baardvark\b\s*((?!\baardvark\b)\b\w+\b\s+)*?){2}$