I'm a Japanese learner of English. I have some questions about the usage of an auxiliary verb "can."
I think the following two sentences are grammatically correct.
Climbing in winter can be dangerous. Your tomorrow's climbing can't be safe.
However, I'm not sure if the following two sentences are also correct.
Climbing in winter can't be safe. Can climbing in winter be dangerous?
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.
Also, in negative sentences and interrogative sentences, "can" expresses specific possibility.
In the dictionary, there isn't a explanation of whether "can" in negative sentences and interrogative sentences is able to express general possibility. So I post this question. I think possibility that climbing in winter is safe/dangerous is general, that is, it happens irregularly several times.