HI, both are right. But, when you use at, you mean that she is there at the moment. If I use in a good school, it means that maybe she’s not there.
Hello Deborah
Prepositions are a funny thing in English. In your example, both IN or AT are correct to use. I will explain why.
Here we are using Prepositions of Place.
When we use IN for a preposition of place, we are talking about an unfixed and non-specific location or 'dentro'. For example. Someone asks me where am I living....I would respond, I live IN Brazil...where specifically, we don't know, IN São Paulo State but the exact specific position is unknown. Another example Where is she? She is IN the class room. Where exactly in the classroom we don't know, but somewhere (dentro da sala).
Now, when we use AT for a preposition of place we are talking about a fixed and specific location. For example: At the bus stop. When we speak about a building, we have an address which is a specific and fixed location. Even when we use @ for an email address. We express Chris @ as 'AT' gmail.com for example. Going back to our last example, where is she? She is IN the classroom and sitting AT her desk.
So, both IN or AT can be used in your example. She studies IN a good school (dentro de uma escola boa) without fixed specific location exactly where she is studying. Or we can also use AT because the school itself has a fixed location and has an address.
Vejo que sua dúvida já foi respondida. Se estiver precisando aprender ingles com aulas focadas em conversação, entre no meu perfil, beleza?
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