Some reflexive verbs pair up with non-reflexive counterparts. Though you can't tell for sure how adding -ся to a verb will affect its meaning, you can sometimes make an intelligent guess.
Познакћмьте менї! Introduce me.
Познакћмьтесь! Get acquainted. (Introduce yourselves.)
Здљсь продаєт учљбники. They sell textbooks here. (3rd plural passive)
Здљсь продаєтся учљбники. Textbooks are sold here. (true passive)
ВІ тђм увќдите большћй дћм. You'll see a big building there.
Увќдимся! See you! (We'll see each other.)
Не беспокћй егћ! Don't bother him.
Не беспокћйся! Don't worry.
Когдђ онђ вернёт кнќгу? When will she return the book?
Когдђ онђ вернётся? When will she return?
Ћн прђвильно произнћсит іто слћво. He pronounces this word correctly.
Кђк произнћсится іто слћво? How is this word pronounced?
Геолћгия менї ћчень интересџет. Geology interests me a lot.
Ї ћчень интересџюсь геолћгией. I'm very interested in geology.
Ћн кћнчил урћк в двђ часђ. He finished the lesson at two o'clock.
Урћк кћнчился в двђ часђ. The lesson was over at two o'clock.
Ђрмия занимђет гћрод. The army is occupying the city.
Ї занимђюсь рџсским языкћм. I'm studying Russian.