Seems “Can” and “May” are not easy to tell apart even for native English speakers.
When we were kids, in school, we always asked permission using “May”, eg
Teacher, may I go to the toilet?
Teacher, may I go to the bookshop to buy one exercise book?
Serina, may I borrow your colour pencils?
To me, using May in these situations sound more polite and respectful.
At times, when my boss was in a hurry, he used to say “Can I have the report right now?”
Otherwise in normal circumstances, he would usually say “May I have the report, you may just leave it on my table once you’ve finished.”
But I think for some reasons it does not sound quite right if you say
May things really be that bad? (x)
Can things really be that bad? (v)
May you smell something burning? (x)
Can you smell something burning? (v)
During winter, it may be very cold here at night.
During winter, it can be very cold here at night. (Which one is more appropriate?)
After reading your posts, this came to my mind.
Hostage1 : Can we live longer?
Hostage2 : How can we live long?
Terrorist : Eat vegetables, do exercise everyday.
Personally, I think this is an exceptional case, seems this is a kind terrorist …..
Maybe “May” is more appropriate? (>_<)''
Sorry, I can’t help much. Hopefully Papa and Uncle Mike Cash could enlighten us.