Hello,
Which one is correct? I’m in the office or I’m at the office? ( while it means "I’m at work) And does it need an article?
Both can be considered correct (yes, the article is needed as you have written it).
in the office - in the room
at the office - in the building but not necessarily in the room, for example, you might have gone to the post room, the staff room, the toilet, the cloakroom, somebody else’s office, the conference room, a meeting, etc.
Thank you Beeesneees and one more question: if we say such sentence: [i]my father isn’t home now, he is in the office[/i], does it mean that he is working?[/b]
That would be the conclusion which the listener draws.
Ok. Thank you so much!