"This is a shoe."

Translation: To jest but.

[karlr42]

Why is "to jest butem"(using instrumental case) wrong? Would it only work if I said something more specific like "Ten przedmiot jest butem"?

[Jellei]

Yes, you're quite right. Simple sentences of the "This is an X"/"These are Y" form take Nominative (and also alwas "to", treated as the subject and not a demonstrative pronoun), defining a noun with another noun takes Instrumental.

[margotgm]

why is 'ten jest but' in correct. ten means 'this'

[mihxal]

"Ten" means "this" but as a determiner describing the noun (in Polish specifically masculine). Not as a standalone pronoun which indicates a nearby object - to this meaning corresponds Polish "to".

"Ten" can be also used in sense "this one" (masculine noun).

[Chris_Rzech]

So buty is plural form of shoe?

[Zimowski]

yes: but - buty

[RamonPadil13]

Can not you say "to but"? As "(ono) to but"?

[Jellei]

You can, it's accepted, but I wouldn't recommend it. On its own, as a super-short sentence, it seems clumsy to me. Also, it's not like "ono to but", because "ono" is really rarely used at all. All constructions like "This/That is X", "These/Those are X", use impersonal "to" as the subject, regardless of the grammatical gender.

[SUNFLOWERGACHA]

Hi there!

[SUNFLOWERGACHA]

Hope its fun learning polish