如何检查一个单词在复数形式中是否更常见，而不是在单词数组中使用单数形式（使用Python / NLTK）？

I'm trying to do the NLTK exercices but I can't do this one. "Which nouns are more common in their plural form, rather than their singular form? (Only consider regular plurals, formed with the -s suffix.)". I spent a day thinking about this and trying things but I just can't get it. Thank you.I'm trying to do the NLTK exercices but I can't