English verb conjugation
COULD TAIL

Regular verb: tail - tailed - tailed

Affirmation

Simple form	V-ing form
I could tail you could tail she could tail we could tail you could tail they could tail	I could be tailing you could be tailing she could be tailing we could be tailing you could be tailing they could be tailing
Perfect	V-ing perfect
I could have tailed you could have tailed she could have tailed we could have tailed you could have tailed they could have tailed	I could have been tailing you could have been tailing she could have been tailing we could have been tailing you could have been tailing they could have been tailing

Negation

Simple form	V-ing form
I couldn't tail you couldn't tail she couldn't tail we couldn't tail you couldn't tail they couldn't tail	I couldn't be tailing you couldn't be tailing she couldn't be tailing we couldn't be tailing you couldn't be tailing they couldn't be tailing
Perfect	V-ing perfect
I couldn't have tailed you couldn't have tailed she couldn't have tailed we couldn't have tailed you couldn't have tailed they couldn't have tailed	I couldn't have been tailing you couldn't have been tailing she couldn't have been tailing we couldn't have been tailing you couldn't have been tailing they couldn't have been tailing

Interrogative form

Simple form	V-ing form
could I tail? could you tail? could she tail? could we tail? could you tail? could they tail?	could I be tailing? could you be tailing? could she be tailing? could we be tailing? could you be tailing? could they be tailing?
Perfect	V-ing perfect
could I have tailed? could you have tailed? could she have tailed? could we have tailed? could you have tailed? could they have tailed?	could I have been tailing? could you have been tailing? could she have been tailing? could we have been tailing? could you have been tailing? could they have been tailing?

Interro-negative form

Simple form	V-ing form
couldn't I tail? couldn't you tail? couldn't she tail? couldn't we tail? couldn't you tail? couldn't they tail?	couldn't I be tailing? couldn't you be tailing? couldn't she be tailing? couldn't we be tailing? couldn't you be tailing? couldn't they be tailing?
Perfect	V-ing perfect
couldn't I have tailed? couldn't you have tailed? couldn't she have tailed? couldn't we have tailed? couldn't you have tailed? couldn't they have tailed?	couldn't I have been tailing? couldn't you have been tailing? couldn't she have been tailing? couldn't we have been tailing? couldn't you have been tailing? couldn't they have been tailing?