using prepositions
1. why do we use the article "the" before "office" for example but not before "school"?

2. what's the difference between " at school" and " at the school"?

what rules do Americans apply to use these kinds of structures?

at the church / at church
at the hospital / in the hospital

mainstream locations

Question

using prepositions
1. why do we use the article "the" before "office" for example but not before "school"?

2. what's the difference between " at school" and " at the school"?

what rules do Americans apply to use these kinds of structures?

at the church / at church
at the hospital / in the hospital

mainstream locations

Answer

We have two kind of articles : definite article (the), and indefinite article (a,an)
So when we say i want an apple it means generally i want an apple doesn’t matter if it is the red one or blue, but when ever we say i want the apple it means i want that specific apple.

Answer

English Grammar in Use by Murphy is well-known.  A paper copy is affordable and a google search will find a PDF.  See unit 74 "The 2 (school / the school)."  Briefly, "church" and "school" do not refer to specific locations, but "the church" and "the school" refer to specific buildings.