Here is a question from a grammar exercise

In He may be from Poland. may means the same as could / might

The answer is could - why? -> I thought may, might, could in this context meant the same.

What is the % of certainty. Did I put these sentences in the right order?

He is/must be from Poland. 100%
He can be from Poland ...
He could be from Poland ...
He may be from Poland. ...
He might be from Poland ...
He can't be from Poland. 0%
I already answered the first part in your other post.

Don't think in terms of percent certainty. You won't learn anything from it except that there is no agreement even among native speakers what the percent certainty is for these words. These are words in a natural language; they are not numbers in mathematics.

By the way, He can be from Poland is not used -- or if it is, it is very rare.

Site Hint: Check out our list of pronunciation videos.
yea, but grammar sometimes looks like mathematics especially when you do such stupid exercises Emotion: smile

Callif Jim thanks for your replies
<<such stupid exercises>>

-- emphasis on "stupid"! Emotion: smile