could tail
Regular verb: tail - tailed- tailed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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	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 	Perfect 	V-ing perfect 	
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	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 	Perfect 	V-ing perfect 	
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? 	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 	Perfect 	V-ing perfect 	
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? 	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?