"She eats breakfast in the morning."
Translation:Hon äter frukost på morgonen.
Prepositions are highly irregular in translation. It's nigh-impossible to give a broad guideline.
I have read that in the context of time Swedish om is equal to English in (as in Filmen börjar om en timme) whereas inom corresponds within (as in Beställ dina varor online och få ditt köp inom en timme). In case you're wondering what's the difference between in and within, this link provides an explanation on the subject. I can't think of any situation where you would use om in a "morning expression".
For the other prepositions it's difficult to give overarching explanations but you could nevertheless find the following collection of morning expressions helpful: i morse = this morning, i går morse = yesterday morning, på måndag morgon = next monday morning , i morgon = tomorrow, i morgon bitti = tomorrow morning.
Swedish uses another preposition than English. Be prepared that time prepositions are usually different.
It is accepted "pa morgonen" or "i morgon" but not i morgonen, for exemple... Is there any rule for it?
på morgonen means 'in the morning' (like, in the early hours of the day) but i morgon means 'tomorrow'.
I'm confused. Duolingo regards"Hon äter frukost i morgon" as an correct answer even though this translates as "She eats breakfast tomorrow". Why?