English verb conjugation
COULD VAIL

Regular verb: vail - vailed - vailed

Affirmation

Simple form	V-ing form
I could vail you could vail she could vail we could vail you could vail they could vail	I could be vailing you could be vailing she could be vailing we could be vailing you could be vailing they could be vailing
Perfect	V-ing perfect
I could have vailed you could have vailed she could have vailed we could have vailed you could have vailed they could have vailed	I could have been vailing you could have been vailing she could have been vailing we could have been vailing you could have been vailing they could have been vailing

Negation

Simple form	V-ing form
I could not vail you could not vail she could not vail we could not vail you could not vail they could not vail	I could not be vailing you could not be vailing she could not be vailing we could not be vailing you could not be vailing they could not be vailing
Perfect	V-ing perfect
I could not have vailed you could not have vailed she could not have vailed we could not have vailed you could not have vailed they could not have vailed	I could not have been vailing you could not have been vailing she could not have been vailing we could not have been vailing you could not have been vailing they could not have been vailing

Interrogative form

Simple form	V-ing form
could I vail? could you vail? could she vail? could we vail? could you vail? could they vail?	could I be vailing? could you be vailing? could she be vailing? could we be vailing? could you be vailing? could they be vailing?
Perfect	V-ing perfect
could I have vailed? could you have vailed? could she have vailed? could we have vailed? could you have vailed? could they have vailed?	could I have been vailing? could you have been vailing? could she have been vailing? could we have been vailing? could you have been vailing? could they have been vailing?

Interro-negative form

Simple form	V-ing form
could I not vail? could you not vail? could she not vail? could we not vail? could you not vail? could they not vail?	could I not be vailing? could you not be vailing? could she not be vailing? could we not be vailing? could you not be vailing? could they not be vailing?
Perfect	V-ing perfect
could I not have vailed? could you not have vailed? could she not have vailed? could we not have vailed? could you not have vailed? could they not have vailed?	could I not have been vailing? could you not have been vailing? could she not have been vailing? could we not have been vailing? could you not have been vailing? could they not have been vailing?