could yank
Regular verb: yank - yanked- yanked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could yank
you could yank
he could yank
we could yank
you could yank
they could yank 	I could be yanking
you could be yanking
he could be yanking
we could be yanking
you could be yanking
they could be yanking	I could have yanked
you could have yanked
he could have yanked
we could have yanked
you could have yanked
they could have yanked	I could have been yanking
you could have been yanking
he could have been yanking
we could have been yanking
you could have been yanking
they could have been yanking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't yank
you couldn't yank
he couldn't yank
we couldn't yank
you couldn't yank
they couldn't yank 	I couldn't be yanking
you couldn't be yanking
he couldn't be yanking
we couldn't be yanking
you couldn't be yanking
they couldn't be yanking	I couldn't have yanked
you couldn't have yanked
he couldn't have yanked
we couldn't have yanked
you couldn't have yanked
they couldn't have yanked	I couldn't have been yanking
you couldn't have been yanking
he couldn't have been yanking
we couldn't have been yanking
you couldn't have been yanking
they couldn't have been yanking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I yank?
could you yank?
could he yank?
could we yank?
could you yank?
could they yank? 	could I be yanking?
could you be yanking?
could he be yanking?
could we be yanking?
could you be yanking?
could they be yanking? 	could I have yanked?
could you have yanked?
could he have yanked?
could we have yanked?
could you have yanked?
could they have yanked? 	could I have been yanking?
could you have been yanking?
could he have been yanking?
could we have been yanking?
could you have been yanking?
could they have been yanking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I yank?
couldn't you yank?
couldn't he yank?
couldn't we yank?
couldn't you yank?
couldn't they yank? 	couldn't I be yanking?
couldn't you be yanking?
couldn't he be yanking?
couldn't we be yanking?
couldn't you be yanking?
couldn't they be yanking? 	couldn't I have yanked?
couldn't you have yanked?
couldn't he have yanked?
couldn't we have yanked?
couldn't you have yanked?
couldn't they have yanked? 	couldn't I have been yanking?
couldn't you have been yanking?
couldn't he have been yanking?
couldn't we have been yanking?
couldn't you have been yanking?
couldn't they have been yanking?