Learn Turkish: Katalogdan başka bir model seçecekken siyah mürekkep bitti. - Just as I was about to choose another model from the catalog, the black ink ran out.

It combines the verb root seç (choose), the future tense suffix -ecek (will/about to), and the adverbial suffix -ken (while). Together, -(y)AcAkken means 'while being about to'. This structure is used to express an intention that was interrupted by another event before it could actually happen.

There is no 'I' in the Turkish sentence. How do we know who was about to choose?

The suffix -ken does not take personal endings. Usually, we look at the main clause to find the subject, but here the main subject is siyah mürekkep (black ink). When the subjects of the two clauses are different, Turkish usually requires you to state the first subject explicitly (e.g., Ben seçecekken...). Because it is omitted here, we rely entirely on context—without it, the sentence could just as easily mean 'Just as he/she was about to choose'.

Why does bitti mean 'ran out' here instead of 'finished'?

The verb bitmek literally means 'to finish' or 'to end'. However, when it is used with consumable items like ink (mürekkep), money (para), or battery power (şarj), it translates naturally to 'run out' or 'die' in English.

Why is katalog marked with the ablative suffix -dan (from)?