Learn Croatian: Klijent pita je li pranje brzo. - The client asks if the washing is fast.

In English, we use 'if' for both conditions ('If it rains...') and reported questions ('He asks if...'). In Croatian, the conditional 'if' is ako, but for reported yes/no questions, you must use je li (or da li). Since the client is reporting a yes/no question, we use je li.

The lesson mentions using standard je li instead of da li. Could I use da li here?

Yes, in everyday spoken Croatian you will often hear Klijent pita da li je pranje brzo. However, standard Croatian grammar prefers je li for reported questions. Notice a key difference in the grammar: with da li, the verb je must be added right after it, but je li already contains the verb je.

Why does brzo end in '-o' here? Is it acting as an adverb?

In this sentence, brzo is an adjective meaning 'fast', not an adverb. It describes the noun pranje (washing). Because verbal nouns like pranje are neuter in Croatian, the adjective must match its gender and takes the neuter singular ending -o.

Could I use the reflexive verb pita se instead of just pita?