1. They moved in yesterday.

Question

2. They moved out the day before yesterday.
3. They moved into yesterday.

4. They moved in the apartment yesterday evening.
5. They moved into the apartment yesterday evening.
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Are they all grammatical except Sentence 3?

6. He is alone at the apartment.
7. He is alone in the apartment.

8. She is alone at the house.
9. She is alone in the house.

10. They are alone at the place.
11. They are alone in the place.

(Are the pairs all correct? Are 'at' and 'in' interchangable?)

Answer 1

3 is incorrect.

The word "in" in these sentences generally means "inside" while "at" could mean either "inside" or "near."