Breakdown of Когда мы получаем посылку от курьера, мы открываем приложение.
мы
we
когда
when
открывать
to open (imperfective)
от
from
Questions & Answers about Когда мы получаем посылку от курьера, мы открываем приложение.
Why do we use от for 'from' here instead of из?
The preposition от is used when you receive something from a person, while из means 'out of' and is used to talk about coming from a place. Because курьер (courier) is a person, we must use от.
Why is the word for courier spelled курьера here?
The preposition от always forces the noun that follows it into the Genitive case. For a masculine noun like курьер, you form the Genitive by adding -а to the end.
Why does посылка change to посылку?
The parcel is the direct object of the verb получаем (we receive), meaning it is the thing being received. This puts it in the Accusative case. Feminine nouns ending in -а change their ending to -у in the Accusative.
приложение (the app) is also a direct object. Why didn't its ending change?
приложение is a neuter noun. For neuter, inanimate objects, the Accusative case form is exactly the same as the dictionary (Nominative) form, so it doesn't change.
Are получаем and открываем perfective or imperfective verbs?
They are both imperfective verbs in the present tense. This sentence describes a general, repeating routine, and imperfective verbs are always used for repeated or habitual actions.