1. There is a garden in the McMurdo Station. [in Antarctica]

1-1. There is a garden inside the McMurdo Station.
2. The scientists are walking at the station.
2-1. The scientists are walking in the station.
2-2. The scientists are walking next to the station.
2-3. The scientists are walking inside the station.

[#1 is the same as #1-1, right? What about #2? When we put 'at', what different meanings does the sentence [#2] have? Which one is similar to #2 among #2-1, #2-2, and #2-3?]

Yes, 1 and 1-1 mean the same thing.

2 and 2-2 mean approximately the same thing.
2-1 and 2-3 mean the same thing.

3. The scientists are eating ramen at the station.

3-1. The scientists are eating ramen in the station.
3-2. The scientists are eating ramen next to the station.

[Thank you for your help. What about #3? Does #3 mean #3-1 or #3-2? Or does #3 mean both?]

In these sentences, the same thing applies: "at" and "in" mean about the same thing. And "next to" means outside the station, but near it.

Yes, #1 is the same as #1-1. Both sentences mean that there is a garden located within the McMurdo Station.

Regarding #2, when "at" is used in the sentence "The scientists are walking at the station," it can have different meanings depending on the context:

- If we interpret it literally, it means that the scientists are walking while being physically present at the location of the station. They could be walking inside the station or in the vicinity of the station.

- #2-1, "The scientists are walking in the station," is similar to #2 in the sense that it implies the scientists are walking inside the station premises.

- #2-2, "The scientists are walking next to the station," implies that the scientists are walking in close proximity to the station but not necessarily inside the premises.

- #2-3, "The scientists are walking inside the station," is similar to #2 and #2-1 as it suggests that the scientists are walking within the confines of the station.

In summary, both #2 and #2-1 can be similar in meaning, whereas #2-2 and #2-3 have slightly different implications.