Could/may/might be my sister, the correct answer, difficult, rain

[emsr2d2]

That's clear to me. Thanks. But why didn't you both use "may"? If I am not mistaken,some native speakers use it for permission not for expressing possibility. I think it was mentioned in one of the threads. Is this why 5jj and you didn't use "may" in your examples?

That's exactly why I didn't use it.

 

[Rachel Adams]

That's exactly why I didn't use it.

But Michael Vince uses. I think sometimes hearing different opinions can be confusing, but not in this case. I find it helpful.
Do I understand the previous explanation correctly, if "could" isn't used in a sentence to refer to ability the only difference between "could" "may" and "might" may be that "could" suggests some idea of circumstances permitting a possibility, might simply suggests the possibility. As 5jj said. Or as I understand it "could" means something is not impossible, while "may" and "might" express a possibility or a prediction. (Prediction=The rain example "it may/might/could rain).
Am I right?

 

[Tarheel]

Different people have different speech habits. The important thing is that you understand what people say and that they understand you.

You might never hear me use one of your example sentences, but you will still (hopefully) understand me. For example, I might say, "I think it's going to rain tomorrow." That's pretty clear, isn't it?

 

[Tdol]

That's clear to me. Thanks. But why didn't you both use "may"? If I am not mistaken,some native speakers use it for permission not for expressing possibility. I think it was mentioned in one of the threads. Is this why 5jj and you didn't use "may" in your examples?

When I went to school and you had to ask permission to enter a schoolteacher's room, some would reply to the question Can I come in? with I don't don't know if you can come in but you may come in. Their pedantry annoyed me in the 1970s. You can use may here, but you don't have to, and most don't nowadays.