Learn Turkish: Testler her yıl zor olur mu? - Do the tests get hard every year?

The phrase her yıl (every year) tells us this is a recurring event or a general habit. The aorist tense (-ur) is used exactly for this kind of general, timeless fact, whereas oluyor mu would sound more like "is it getting hard right now?".

Why do we need the verb olur here? Couldn't we just ask Testler her yıl zor mu?

You could ask that, and it would simply mean "Are the tests hard every year?" But using olmak (to be / to become) in the aorist as zor olur adds the feeling of "do they turn out hard?" or "do they get hard?". It emphasizes the regular outcome or event of the tests taking place.

Testler is plural. Why doesn't the verb take a plural suffix, like olurlar mı?

In Turkish grammar, when the subject is plural but not human (like tests, objects, or animals), the verb generally stays in the singular form. That is why we use olur mu instead of olurlar mı.

The verb root is ol-, which is one syllable. Shouldn't the aorist suffix be -ar instead of -ur?