Breakdown of Он прочитал письмо, затем позвонил другу.
он
he / it (for a masculine noun) / it (for a neuter noun)
друг
friend
письмо
letter
звонить
to call
Questions & Answers about Он прочитал письмо, затем позвонил другу.
Why are both verbs in this sentence perfective (прочитал and позвонил)?
Both actions are single, completed events that happened one after the other. When narrating a sequence of finished actions in the past, Russian uses the perfective aspect for all the verbs to show that one action ended before the next began.
Could I use потом instead of затем here?
Yes, absolutely. Both затем and потом mean 'then' or 'after that' and are used to show a sequence of events. затем can sound slightly more formal or written, but they are mostly interchangeable in a sentence like this. Just avoid using тогда, which means 'then' in the sense of 'at that time' or 'in that case'.
Why is the word for friend in the dative case (другу) instead of the accusative case?
In English, you call someone directly, but in Russian, the verb позвонить (to call by phone) requires the dative case. You can think of it as giving a ring 'to' someone. Because the action is directed toward the person, you must use другу.
The English translation says 'his friend', so why isn't there a word like своему before другу?
Russian often drops possessive pronouns when the owner is obvious from the context. Since it is his own friend he is calling, adding своему or его is not grammatically wrong, but it sounds unnatural and redundant to a native speaker.