Joining Clauses: že or aby, lebo or hoci

Clauses are joined by a conjunction after a comma. Choose it by meaning and by the verb that follows:

• že (that) reports a fact: Viem, že máš pravdu. aby (so that, to) expresses a wish, request or purpose and takes the past form: Chcem, aby si prišiel.
• lebo (because) gives a reason, preto (so, therefore) a result, hoci (although) a contrast.
• a (and) adds, also between single words, with no comma: čaj a káva. ale (but) contrasts; after nie always use ale.
• keď (when, whenever) and ak (if) are for real situations. keby (if) is unreal: it takes the past form, with by in the other clause.
• kým means until: Počkaj, kým prídem. (Wait until I come.) It often takes a negated verb with the same meaning: Nepôjdeš von, kým neupraceš izbu. (You won't go out until you tidy your room.)