How could? 怎么可能 Meaning, there is a pre-existing method of resolution. What are my options? How can? 怎么会 Meaning, there has not been a developed resolution. What can be we do? ~Joke to help remember the difference between **May**: A form of could **Can**: Development of knowledge or skill Joke: "Can I go to the bathroom (toilet)?" I don't know, can you? Do you know how to? "May I go the bathroom?" Yes, but not right now, there is not a toilet available. (knows how to go the bathroom, however the best practice solution is not available). I am a boy, may I go in the bushes? (alternate option) No, you may not. It is bad manners to pee in the bushes in an urban environment.

How come ...? How can it be? How could this be possible? How on earth? How the hell/etc...?

OK, thank you

“怎么可能” = how come? “怎么会” - 这个。。在不同的上下文中翻译不一样，所以呀 it depends on the context.