I want to ask a question about the usage of an auxiliary verb "can."
I think the next sentence is grammatically incorrect.
This story can be true.
In contrast, I think the next sentence is correct.
This story could[might/may] be true.
Is my understanding right?
In a dictionary, I learned about "can" that expresses possibility (not ability or permission) as follows:
In positive sentences, "can" expresses general possibility, that is, possibility that a thing happens irregularly several times, and "can" isn't able to express specific possibility, that is, possibility that a thing happens specifically only once.
For example, the next sentence is not correct.
It can rain tomorrow.
In contrast, the following sentence is correct.
It may rain tomorrow.
(I think not only "may" but also "could"/"might" are correct.)
That's why I thought "This story can be true" is not correct. For possibility that this story is true is specific, that is, it happens specifically only once.