Is "could" interchangeable with "can"?
for example, there are coversations like these:
A: I could run faster than you.
B: No way.
In this case, the "could" is referring to the less certain possibility of a skill in the present time.
A: Even that small stadium could have ten thousand people.
B: Isn't that too small for ten thousand people?
In this case, the "could" is referring to the less certain possibility of a capability as a fact.
I think these "could"s in the two examples express the same things as "can", and the difference from" can" is just that "could" is less certain about possibilities.
However, I'm not sure if it's allowed to use "could" like those, because "could" is used when expressing hypothetical or conditional things like "would".
Are the "could"s acceptable?