Learn Farsi: پرواز ما دقیقاً پنج ساعت طول می‌کشد.

This lesson teaches how to say it takes a certain amount of time to do something. Because this sentence just says a noun (our flight) takes time, there is no second action. You only use tâ and a subjunctive verb when you are adding that second action, like saying 'It takes five hours to arrive'.

Why does the word دقیقاً end with an alef and two little lines at the top?

Those two lines are an ending borrowed from Arabic called tanvin. In Farsi, it is pronounced '-an' and is used to turn an adjective into an adverb. Here, it changes the adjective دقیق (exact or precise) into the adverb دقیقاً (exactly).

Why do we use طول می‌کشد for 'takes' instead of a form of گرفتن?

While گرفتن (to take) is used for physically taking objects, Farsi uses a very specific compound verb for the passage of time: طول کشیدن. The word طول means 'length' and کشیدن means 'to draw' or 'to stretch'. So, saying a flight takes five hours literally translates to saying it 'draws out a length' of five hours.

How do we connect the words for 'flight' and 'our' in پرواز ما?

You connect them using the ezafe vowel sound '-e', pronouncing the phrase as parvâz-e mâ. As a quick refresher, the ezafe links a noun to its possessor or to an adjective, and it usually isn't written out as a separate letter in the standard Farsi alphabet.