I've been wondering about the difference between questions that use can't you and can you not. Like:
- Can't you tell just by looking? [I read this from a comic-detective series]
- Can you not hear me? [I heard this from an animation movie]
So, does it make a difference when you use can't you and can you not? Or anything else like it, such as is it not and isn't it?
I also find that question tags often use those two types of tags, which in my mind are somewhat not interchangeable, such as:
- It's surprisingly hard to find, is it not?
- It's surprisingly hard to find, isn't it?
I think both forms are grammatically correct, but I can't figure how they differ each other.