Learn Turkish: Zarfı hemen yırtıverdi. - He quickly tore the envelope.

It comes from the verb root yırt- (to tear). We add the suddenness suffix -ıver to show the action was done quickly or abruptly. Finally, the past tense suffix -di is added to make it past tense.

If -ıver already means "quickly", why is the word hemen also in the sentence?

It is very common in Turkish to use an adverb of speed like hemen (immediately) or çabucak (quickly) alongside a verb with the -(y)iver suffix. It is not considered a mistake, but rather a way to add extra emphasis to highlight just how fast or sudden the action was.

How does vowel harmony affect the -(y)iver suffix in yırtıverdi?

The first vowel of the -(y)iver suffix follows 4-way vowel harmony based on the verb root. Since the vowel in yırt- is ı, it becomes -ıver. However, the e in the -ver part never changes, which means any suffix added after it, like the past tense -di, will always harmonize with e.

Why does zarf have an -ı on the end?

The suffix -ı is the definite accusative case marker. It shows that zarf (envelope) is the specific direct object of the action. It indicates he tore "the" envelope, not just any envelope.