以下哪对是正确的对应单复数形式？

Which is the correct singular-plural pair?

youdao

这个词单位单复数形式相同。

This word has the same form in the singular as in the plural.

youdao

初步学会一些简单名词的单，复数形式。

Can learn some simple noun from single to plural.

youdao

初步学会一些简单名词的单，复数形式。

Can learn some simple noun from single to plural.

youdao