_______ I go to the toilet, please? (to show respect)
May / Could
What ______ they do yesterday?
could - They could play piano.
What _______ she do?
can - She can dance.
You ______ go home now. (to be very nice)
may
_______ he ride a bicycle?
Can - Yes, he can.
You _______(not) shout when I am speaking. (someone you know)
can't
________ you swim when you were 1 years old?
Could - No, I couldn't.
______ you read me a book? (to be very nice)
May / Could