请注意单词模型——为复数形式。

Notice the use of the word models - plural.

youdao

这个单词只有单数形式，没有复数形式。

This noun appears in the singular form, never in the plural form.

youdao

很多英文单词的单复数形式没差别，因此有时你会听到有人说为一篇文章做了“很多调查研究”，但这么说也很讨喜。

Many English words are the same in the singular as in the plural, so sometimes you will hear someone talk about the "researches" they did for a story, which is nonetheless endearing.

youdao