English verb conjugation
COULD AIRMAIL

Regular verb: airmail - airmailed - airmailed

Affirmation

Simple form	V-ing form
I could airmail you could airmail he could airmail we could airmail you could airmail they could airmail	I could be airmailing you could be airmailing he could be airmailing we could be airmailing you could be airmailing they could be airmailing
Perfect	V-ing perfect
I could have airmailed you could have airmailed he could have airmailed we could have airmailed you could have airmailed they could have airmailed	I could have been airmailing you could have been airmailing he could have been airmailing we could have been airmailing you could have been airmailing they could have been airmailing

Negation

Simple form	V-ing form
I couldn't airmail you couldn't airmail he couldn't airmail we couldn't airmail you couldn't airmail they couldn't airmail	I couldn't be airmailing you couldn't be airmailing he couldn't be airmailing we couldn't be airmailing you couldn't be airmailing they couldn't be airmailing
Perfect	V-ing perfect
I couldn't have airmailed you couldn't have airmailed he couldn't have airmailed we couldn't have airmailed you couldn't have airmailed they couldn't have airmailed	I couldn't have been airmailing you couldn't have been airmailing he couldn't have been airmailing we couldn't have been airmailing you couldn't have been airmailing they couldn't have been airmailing

Interrogative form

Simple form	V-ing form
could I airmail? could you airmail? could he airmail? could we airmail? could you airmail? could they airmail?	could I be airmailing? could you be airmailing? could he be airmailing? could we be airmailing? could you be airmailing? could they be airmailing?
Perfect	V-ing perfect
could I have airmailed? could you have airmailed? could he have airmailed? could we have airmailed? could you have airmailed? could they have airmailed?	could I have been airmailing? could you have been airmailing? could he have been airmailing? could we have been airmailing? could you have been airmailing? could they have been airmailing?

Interro-negative form

Simple form	V-ing form
couldn't I airmail? couldn't you airmail? couldn't he airmail? couldn't we airmail? couldn't you airmail? couldn't they airmail?	couldn't I be airmailing? couldn't you be airmailing? couldn't he be airmailing? couldn't we be airmailing? couldn't you be airmailing? couldn't they be airmailing?
Perfect	V-ing perfect
couldn't I have airmailed? couldn't you have airmailed? couldn't he have airmailed? couldn't we have airmailed? couldn't you have airmailed? couldn't they have airmailed?	couldn't I have been airmailing? couldn't you have been airmailing? couldn't he have been airmailing? couldn't we have been airmailing? couldn't you have been airmailing? couldn't they have been airmailing?