Yes-no questions with li

Since A1 you have asked yes-no questions with da li: Da li imate iskustva? You have also been hearing a second, shorter way all along: Imate li iskustva? Here the verb moves to the front and the little word li follows it directly. Both mean the same thing, both are correct, and both are everyday Serbian: da li is extremely common in speech, while verb + li is shorter and a little crisper, and is the form you will meet most in writing. Neither is wrong.

The pattern: verb first, li straight after it

1. Take the statement: Imate iskustva. (You have experience.)
2. Put the verb first: Imate...
3. Put li right after it: Imate li iskustva?

li is a clitic, and in the clitic cluster you learned in the previous lesson it always stands first. So any other clitics come after li, never between the verb and li: Možete li mi poslati ugovor? (li, then mi). Hoćeš li ga zvati? For the future, the verb that goes first is the full form of hteti: Hoćete li doći na razgovor?

biti: use the long form

The short forms of biti (sam, si, je...) are clitics, and a clitic can never open a sentence. So in a li-question you use the long form instead: jesam, jesi, jesmo, jeste, jesu. The one exception is the third person singular: everyone says je li, not jeste li, and in speech it is often shortened to je l'. This works both with biti on its own and with the past tense, where biti is the helper verb: Jesi li poslao biografiju?

Do not start a question with Si li...: the short form cannot come first. Write Jesi li. And for he/she/it, use Je li, not Jeste li — Jeste li is the polite or plural you.

Negative questions

A negative verb can stand first too. With an ordinary verb, ne stays glued in front of it and li follows the pair: Ne znate li gde je šalter? With the fused negatives (nisam, nisi, nije, nemam, neću...) the whole word goes first: Nisi li dobio poziv? Nemate li vremena? These questions often expect a yes: the speaker thinks the answer is probably positive.

Either-or questions with ili

To offer a choice, ask the li-question and add the second option with ili: Želite li raditi ujutru ili popodne? Radite li u kancelariji ili od kuće? li still comes only once, after the first verb.

li inside a longer sentence

In A2 you embedded questions with da li: Ne znam da li je slobodan. The same inversion works inside a sentence: put the verb of the inner question first and li after it. Ne znam je li slobodan. Pitao me je imam li vozačku dozvolu. Zanima me jesu li stigli rezultati. The question mark disappears, because the whole sentence is now a statement.

Never put both: Da li imate li... is wrong. Choose Da li imate...? or Imate li...?