Learn Turkish: Kim biliyor?

The root of the verb "to know" is bil-, which ends in a consonant. To add the -yor suffix, we need a connecting vowel. Because the vowel in bil- is i, 4-way vowel harmony rules tell us to use i as the connecting vowel. We put them together to get bil- + -iyor = biliyor.

Why does this translate to "Who knows" instead of "Who is knowing"?

In English, we use the simple present tense for mental states like knowing, wanting, or liking (e.g., "I know", not "I am knowing"). However, Turkish frequently uses the present continuous -iyor tense for these exact same verbs. So, while biliyor literally means "is knowing", we translate it to "knows" because that is how we express the same idea in English.

Where is the personal suffix on the verb biliyor?

The question word kim (who) acts as a third-person singular subject, just like "he", "she", or "it". In Turkish, the third-person singular does not take any extra personal suffix at the end of the verb. It is just left as biliyor.

Why isn't there a question particle like "mi" at the end of this sentence?