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 couldn't vail you couldn't vail she couldn't vail we couldn't vail you couldn't vail they couldn't vail	I couldn't be vailing you couldn't be vailing she couldn't be vailing we couldn't be vailing you couldn't be vailing they couldn't be vailing
Perfect	V-ing perfect
I couldn't have vailed you couldn't have vailed she couldn't have vailed we couldn't have vailed you couldn't have vailed they couldn't have vailed	I couldn't have been vailing you couldn't have been vailing she couldn't have been vailing we couldn't have been vailing you couldn't have been vailing they couldn't 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
couldn't I vail? couldn't you vail? couldn't she vail? couldn't we vail? couldn't you vail? couldn't they vail?	couldn't I be vailing? couldn't you be vailing? couldn't she be vailing? couldn't we be vailing? couldn't you be vailing? couldn't they be vailing?
Perfect	V-ing perfect
couldn't I have vailed? couldn't you have vailed? couldn't she have vailed? couldn't we have vailed? couldn't you have vailed? couldn't they have vailed?	couldn't I have been vailing? couldn't you have been vailing? couldn't she have been vailing? couldn't we have been vailing? couldn't you have been vailing? couldn't they have been vailing?