Learn Farsi: کسی باید در آشپزخانه کثیف‌کاری کرده باشد. - Someone must have made a mess in the kitchen.

To express a logical deduction about the past (saying something "must have" happened), Farsi uses باید (bâyad) followed by the Present Perfect Subjunctive. In this sentence, we use باید along with کرده باشد (karde bâshad). It literally translates to "must that someone have done."

Why is the auxiliary verb باشد (bâshad) used at the end instead of است (ast)?

A standard Present Perfect verb would use است (ast) for the third person singular, like کرده است (karde ast - "has done"). However, the word باید requires the following verb to be in the subjunctive mood. To make the Present Perfect Subjunctive, we simply replace the indicative است with the subjunctive باشد.

What is the literal translation of کثیف‌کاری (kasif-kâri)?

It translates literally to "dirty work" or "mess-making." It combines کثیف (kasif, meaning "dirty") and کاری (kâri, meaning "work" or "action"). When paired with the verb کردن (kardan, "to do"), the compound verb کثیف‌کاری کردن means "to make a mess."

Why is there an ی at the end of کسی (kasi)?

The base word کس (kas) means "person." Adding the indefinite suffix ی (i) to the end changes it to mean "a person" or, more commonly, "someone" or "somebody."