could tunnel
Regular verb: tunnel - tunnelled- tunnelled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could tunnel
you could tunnel
he could tunnel
we could tunnel
you could tunnel
they could tunnel 	I could be tunnelling
you could be tunnelling
he could be tunnelling
we could be tunnelling
you could be tunnelling
they could be tunnelling	I could have tunnelled
you could have tunnelled
he could have tunnelled
we could have tunnelled
you could have tunnelled
they could have tunnelled	I could have been tunnelling
you could have been tunnelling
he could have been tunnelling
we could have been tunnelling
you could have been tunnelling
they could have been tunnelling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't tunnel
you couldn't tunnel
he couldn't tunnel
we couldn't tunnel
you couldn't tunnel
they couldn't tunnel 	I couldn't be tunnelling
you couldn't be tunnelling
he couldn't be tunnelling
we couldn't be tunnelling
you couldn't be tunnelling
they couldn't be tunnelling	I couldn't have tunnelled
you couldn't have tunnelled
he couldn't have tunnelled
we couldn't have tunnelled
you couldn't have tunnelled
they couldn't have tunnelled	I couldn't have been tunnelling
you couldn't have been tunnelling
he couldn't have been tunnelling
we couldn't have been tunnelling
you couldn't have been tunnelling
they couldn't have been tunnelling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I tunnel?
could you tunnel?
could he tunnel?
could we tunnel?
could you tunnel?
could they tunnel? 	could I be tunnelling?
could you be tunnelling?
could he be tunnelling?
could we be tunnelling?
could you be tunnelling?
could they be tunnelling? 	could I have tunnelled?
could you have tunnelled?
could he have tunnelled?
could we have tunnelled?
could you have tunnelled?
could they have tunnelled? 	could I have been tunnelling?
could you have been tunnelling?
could he have been tunnelling?
could we have been tunnelling?
could you have been tunnelling?
could they have been tunnelling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I tunnel?
couldn't you tunnel?
couldn't he tunnel?
couldn't we tunnel?
couldn't you tunnel?
couldn't they tunnel? 	couldn't I be tunnelling?
couldn't you be tunnelling?
couldn't he be tunnelling?
couldn't we be tunnelling?
couldn't you be tunnelling?
couldn't they be tunnelling? 	couldn't I have tunnelled?
couldn't you have tunnelled?
couldn't he have tunnelled?
couldn't we have tunnelled?
couldn't you have tunnelled?
couldn't they have tunnelled? 	couldn't I have been tunnelling?
couldn't you have been tunnelling?
couldn't he have been tunnelling?
couldn't we have been tunnelling?
couldn't you have been tunnelling?
couldn't they have been tunnelling?