Learn Polish: Wszyscy powinni segregować śmieci. - Everyone should sort the garbage.

The word for "should" changes its ending based on who is doing the action. Because the subject is wszyscy (a group of people), we must use the masculine personal plural form, which is powinni.

In English, "everyone" is a singular word (we say "everyone is"). Is wszyscy plural?

Yes! This is a very common trap for English speakers. While wszyscy translates to "everyone", it literally means "all" (as in "all people"). Therefore, it is always grammatically plural and must be followed by plural verbs like powinni.

Why is segregować in its dictionary form?

When you use a form of powinien to give advice, the main action verb that follows it must be in the infinitive (dictionary) form. This works exactly like English: you say "should sort", not "should sorts".

What case is śmieci in?

It is in the accusative case because it is the direct object of the verb segregować. The word śmieci is a plural noun (meaning garbage or trash), and for non-living things in the plural, the accusative form looks exactly the same as the nominative form.