I can mail you can mail he can mail we can mail you can mail they can mail
V-ing form
I can be mailing you can be mailing he can be mailing we can be mailing you can be mailing they can be mailing
Perfect
I can have mailed you can have mailed he can have mailed we can have mailed you can have mailed they can have mailed
V-ing perfect
I can have been mailing you can have been mailing he can have been mailing we can have been mailing you can have been mailing they can have been mailing
Negation
Simple form
I cannot mail you cannot mail he cannot mail we cannot mail you cannot mail they cannot mail
V-ing form
I cannot be mailing you cannot be mailing he cannot be mailing we cannot be mailing you cannot be mailing they cannot be mailing
Perfect
I cannot have mailed you cannot have mailed he cannot have mailed we cannot have mailed you cannot have mailed they cannot have mailed
V-ing perfect
I cannot have been mailing you cannot have been mailing he cannot have been mailing we cannot have been mailing you cannot have been mailing they cannot have been mailing
Interrogative form
Simple form
can I mail? can you mail? can he mail? can we mail? can you mail? can they mail?
V-ing form
can I be mailing? can you be mailing? can he be mailing? can we be mailing? can you be mailing? can they be mailing?
Perfect
can I have mailed? can you have mailed? can he have mailed? can we have mailed? can you have mailed? can they have mailed?
V-ing perfect
can I have been mailing? can you have been mailing? can he have been mailing? can we have been mailing? can you have been mailing? can they have been mailing?
Interro-negative form
Simple form
can I not mail? can you not mail? can he not mail? can we not mail? can you not mail? can they not mail?
V-ing form
can I not be mailing? can you not be mailing? can he not be mailing? can we not be mailing? can you not be mailing? can they not be mailing?
Perfect
can I not have mailed? can you not have mailed? can he not have mailed? can we not have mailed? can you not have mailed? can they not have mailed?
V-ing perfect
can I not have been mailing? can you not have been mailing? can he not have been mailing? can we not have been mailing? can you not have been mailing? can they not have been mailing?