Learn Polish: Czy wiesz, kto wymyślił ten powszechny mit? - Do you know who made up this widespread myth?

Polish has two verbs for "to know". Znać means to be familiar with a person, place, or noun. Wiedzieć means to know a fact or piece of information, and it is the verb you must use before question words like kto (who), co (what), or a conjunction like że (that).

Why doesn't ten powszechny mit change its ending even though it is the direct object of the sentence?

It is actually in the accusative case, which is required for direct objects. However, because mit (myth) is a masculine inanimate noun, its accusative form looks exactly the same as its basic nominative dictionary form.

Why is the perfective verb wymyślił used here instead of an imperfective form?

Wymyślić is perfective. We use it here because the sentence focuses on a single, completed action in the past: the specific event of someone successfully inventing this myth. The imperfective wymyślał would mean "was making up" or "used to make up" over a period of time.

Why is there a comma before kto?

In Polish, you must almost always put a comma before a subordinate clause. Whenever a sentence introduces a new clause with a question word like kto (who), co (what), or a conjunction like że (that), a comma is strictly required.