Breakdown of دربارهی این قتل، من شک دارم که او واقعیت را گفته باشد.
من
I
او
he/she
این
this
گفتنgoftan
to say / to tell
Questions & Answers about دربارهی این قتل، من شک دارم که او واقعیت را گفته باشد.
Why is the verb gofteh bâshad used here instead of the regular present perfect gofteh ast?
This highlights the core of your current lesson! The phrase shak dâram (I doubt) expresses uncertainty, which requires the subjunctive mood. Because the action you are doubting already happened in the past ("he has told"), you must use the Present Perfect Subjunctive. It is built by combining the past participle gofteh with bâshad (the present subjunctive of "to be" for "he/she").
What is the purpose of the -ye sound at the end of darbâre-ye?
This is the ezâfe linking the preposition darbâre (about) to the noun phrase in qatl (this murder). Because darbâre ends in a silent "h" (which creates an "e" vowel sound), the ezâfe takes the form of a -ye sound to bridge the gap smoothly.
Why do we use the object marker râ after vâqeyat?
vâqeyat (reality / the truth) is the direct object of the verb "to tell." Because the speaker is referring to the specific truth regarding this particular murder, the object is definite and requires the definite object marker râ.
Could I use râst instead of vâqeyat for "truth" in this sentence?
Yes, but the grammar would change slightly. "To tell the truth" is typically expressed with the compound verb râst goftan, which does not take because it is a general concept. If you used it here, you would simply say . The word means "reality" or "the facts", so translates more literally to "has told the actual facts [of this case]".