Learn Turkish: Soğuk hava girmesin diye kovanın deliklerini kapattım. - I closed the holes of the hive so that cold air doesn't enter.

girmesin is the third-person negative imperative of girmek (to enter), literally meaning 'let it not enter'. In Turkish, combining an imperative or optative verb with diye (literally 'saying') is the standard way to form a purpose clause, meaning 'so that an action happens or doesn't happen'.

Why are there two -i sounds at the end of deliklerini?

Let's break it down: delik (hole) + -ler (plural) + -i (possessive 'its', linking it to kovanın, the hive's). That gives us delikleri (its holes). Finally, we add the accusative case -i (which becomes -ni with a buffer letter 'n') because these specific holes are the direct object of the main verb kapattım (I closed).

Why isn't soğuk hava marked with an accusative case ending?

Even though it comes before a verb, soğuk hava (cold air) is the subject of the mini-sentence inside the purpose clause. It is the thing that we don't want doing the entering (girmesin). Subjects always stay in the plain nominative form, taking no case endings.

Is the verb kapattım related to the word kapalı (closed) or kapı (door)?