Student or Learner
What is the difference between in and at? I have seen both of these sentences. Are they different?
1. He is in the pool.
2. He is at the pool.
in the restaurant
at the restaurant
Is there any rule to learn the difference?
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.