Learn Farsi: پژوهشگر از ورزشکار سوال می‌پرسید. - The researcher was asking the athlete a question.

Both suffixes mean "someone who does X" and are used to form professions or agent nouns. پژوهشگر combines the noun پژوهش (research) with -گر to mean "researcher". ورزشکار combines ورزش (sport) with -کار to mean "athlete".

Why does the sentence use the preposition از (from) before the athlete?

In Farsi, you don't "ask someone" a question; you "ask a question from someone". The verb پرسیدن (to ask) requires the preposition از (from) to indicate the person being asked. That is why the sentence literally says از ورزشکار (from the athlete).

If می‌پرسید already means "was asking", why do we need the word سوال here?

While می‌پرسید by itself means "was asking", Farsi speakers frequently use the compound phrase سوال پرسیدن (literally "to ask a question") to sound more natural and complete. It functions just like the English phrasing "asking a question" rather than simply "asking".

What tense is می‌پرسید and how is it formed?

It is the past continuous tense, which shows an ongoing action in the past ("was asking"). You form it by adding the continuous prefix می‌ to the simple past verb پرسید (he/she asked).