Questions & Answers about تو دیشب کجا بودی؟
How do we form budi to mean you were?
In the simple past tense, the base of the verb to be is bud. To show who we are talking about, we attach a personal ending. Here, we add -i for you (informal, singular). So, bud plus -i gives us budi (you were).
Why is the question word koja (where) placed right before the verb?
Farsi word order is different from English. Question words like koja (where), key (when), or chi (what) usually sit right before the verb near the end of the sentence. The natural order here is Subject (to) plus Time (dishab) plus Question Word (koja) plus Verb (budi).
Could I drop the word to (you) and still be understood?
Absolutely. In Farsi, the verb ending already tells us who the subject is. Since the -i on the end of budi specifically means you, asking dishab koja budi? is perfectly natural and very common.
I recognize shab means night. Where does the di in dishab come from?
The prefix di- is used to talk about the previous day. You might also recognize it from diruz (yesterday). Combined with shab (night), it translates to yesterday night or last night.