Hello! I'm struggling a little bit with this one and was wondering if someone could help me. 'στο στρατό' is given in accusative, but I would have thought we did this bit in genitive, ie, 'του στρατού'. Is anyone able to explain why the correct formulation is in acc?
Both are correct. In this case,they are interchangeable, since there is no serious context issue. It's added as an alternative and it should be accepted, you can use either of them. ^.^
Keep in mind though, these cases are few. Genitive and accusative are not always interchangeable.