English verb conjugation
COULD UNNAIL

Regular verb: unnail - unnailed - unnailed

Affirmation

Simple form	V-ing form
I could unnail you could unnail he could unnail we could unnail you could unnail they could unnail	I could be unnailing you could be unnailing he could be unnailing we could be unnailing you could be unnailing they could be unnailing
Perfect	V-ing perfect
I could have unnailed you could have unnailed he could have unnailed we could have unnailed you could have unnailed they could have unnailed	I could have been unnailing you could have been unnailing he could have been unnailing we could have been unnailing you could have been unnailing they could have been unnailing

Negation

Simple form	V-ing form
I couldn't unnail you couldn't unnail he couldn't unnail we couldn't unnail you couldn't unnail they couldn't unnail	I couldn't be unnailing you couldn't be unnailing he couldn't be unnailing we couldn't be unnailing you couldn't be unnailing they couldn't be unnailing
Perfect	V-ing perfect
I couldn't have unnailed you couldn't have unnailed he couldn't have unnailed we couldn't have unnailed you couldn't have unnailed they couldn't have unnailed	I couldn't have been unnailing you couldn't have been unnailing he couldn't have been unnailing we couldn't have been unnailing you couldn't have been unnailing they couldn't have been unnailing

Interrogative form

Simple form	V-ing form
could I unnail? could you unnail? could he unnail? could we unnail? could you unnail? could they unnail?	could I be unnailing? could you be unnailing? could he be unnailing? could we be unnailing? could you be unnailing? could they be unnailing?
Perfect	V-ing perfect
could I have unnailed? could you have unnailed? could he have unnailed? could we have unnailed? could you have unnailed? could they have unnailed?	could I have been unnailing? could you have been unnailing? could he have been unnailing? could we have been unnailing? could you have been unnailing? could they have been unnailing?

Interro-negative form

Simple form	V-ing form
couldn't I unnail? couldn't you unnail? couldn't he unnail? couldn't we unnail? couldn't you unnail? couldn't they unnail?	couldn't I be unnailing? couldn't you be unnailing? couldn't he be unnailing? couldn't we be unnailing? couldn't you be unnailing? couldn't they be unnailing?
Perfect	V-ing perfect
couldn't I have unnailed? couldn't you have unnailed? couldn't he have unnailed? couldn't we have unnailed? couldn't you have unnailed? couldn't they have unnailed?	couldn't I have been unnailing? couldn't you have been unnailing? couldn't he have been unnailing? couldn't we have been unnailing? couldn't you have been unnailing? couldn't they have been unnailing?