Use of in and at
a) Mary lives in sucre and mejia street. OR
b) Mary lives at sucre and mejia street

I guess, it's correct "a)Mary lives in sucre and mejia street. " because I know that Mary lives in that street... But what happens if I'm not sure that Mary lives there... can I use AT for those cases?

c) She is studying at San Pedro Pascual High School. OR
d) She is studying in San Pedro Pascual High School.

I guess, both are correct but it depends if someone suppose that someone is in that place, in this case we use AT?
and when we are sure that someone is in that place we use IN?

e) Michael is doing a short walk on the street. Is it correct?
f) Michael is doing a short walk in the street

Question

Use of in and at
a) Mary lives in sucre and mejia street. OR
b) Mary lives at sucre and mejia street

I guess, it's correct "a)Mary lives in sucre and mejia street. " because I know that Mary lives in that street... But what happens if I'm not sure that Mary lives there... can I use AT for those cases?

c) She is studying at San Pedro Pascual High School. OR
d) She is studying in San Pedro Pascual High School.

I guess, both are correct but it depends if someone suppose that someone is in that place, in this case we use AT?
and when we are sure that someone is in that place we use IN?

e) Michael is doing a short walk on the street. Is it correct? 
f) Michael is doing a short walk in the street

Answer

Hi Soffy,

- I would say that Mary lives ON Sucre Street, or she lives ON Mejia Street. She cannot live on both, UNLESS you want to say that she lives AT THE CORNER OF Sucre and Mejia Streets. (I believe that one can also say that Mary lives in Sucre Street, but I more commonly hear "on". That could depend on whether you are in England or in North America, but I'm not entirely certain).
- If you are not sure that Mary lives there, you would simple say so: "I think that Mary lives on Sucre Street". You can also add, "But I'm not sure".
- She is studying IN high school (or simply, she is IN high school), BUT she is studying AT San Pedro Pascual High School. Again, if you aren't sure if she is studying there, you would say so: "I think/believe/assume she is studying there".
- Michael is TAKING/GOING FOR a short walk UP/DOWN the street. If he weren't going for a walk, but was outside on the pavement, you could say, for example, that he was standing IN the street.

Hopefully, that all makes sense.

Answer

They sound both normal, and if you were speaking to someone and said that, they wouldn't freak out or anything. 
Except walking in a street. It would be on a street.

Answer

Hey Soffy!

b) Mary lives at sucre and mejia street

This is the correct answer. If you say, "Mary lives IN Sucre and Mejia Street", suena como si ella vive físicamente DENTRO de la calle. (perdoname, mi español no es muy bueno).

c) She is studying at San Pedro Pascual High School.

This is the correct answer. "I study IN San Pedo Pascual High school" quiere decir que los estudiantes estudian solamente dentro del edificio, y que nunca estudian fuera de ese lugar "At" es una palabra mas..."abierta" o "flexible."

e) Michael is doing a short walk on the street 
f) Michael is doing a short walk in the street

En ingles, no dijimos ninguna de estas dos frases. Dijimos, "Michael is taking a walk", o, "Michael is taking a walk outside." En esta situacion, las palabras, "in the street", no se usan porque son redundante. Ya sabemos que si el esta caminando afuera, está caminando por la calle.