English verb conjugation
COULD TAIL

Regular verb: tail - tailed - tailed

Affirmation

Simple form	V-ing form
I could tail you could tail he could tail we could tail you could tail they could tail	I could be tailing you could be tailing he 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 he 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 he 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 he 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 he 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 he 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 he 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 he tail? could we tail? could you tail? could they tail?	could I be tailing? could you be tailing? could he 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 he 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 he 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 he 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 he 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 he 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 he have been tailing? couldn't we have been tailing? couldn't you have been tailing? couldn't they have been tailing?