The 2th sentence in De Bello Gallico Liber I.
Hi omnes lingua, institutis, legibus inter se differunt.
lingua is put Ablative Singular. Why?
I am not a native speaker of Indo-European languages. It is hard for me to understand how one language can differ from each other (inter se differunt).
And the following 2 words are put in Ablative Plural. Only lingua is put in Ablative Singular.