could staple
Regular verb: staple - stapled- stapled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could staple
you could staple
he could staple
we could staple
you could staple
they could staple 	I could be stapling
you could be stapling
he could be stapling
we could be stapling
you could be stapling
they could be stapling	I could have stapled
you could have stapled
he could have stapled
we could have stapled
you could have stapled
they could have stapled	I could have been stapling
you could have been stapling
he could have been stapling
we could have been stapling
you could have been stapling
they could have been stapling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't staple
you couldn't staple
he couldn't staple
we couldn't staple
you couldn't staple
they couldn't staple 	I couldn't be stapling
you couldn't be stapling
he couldn't be stapling
we couldn't be stapling
you couldn't be stapling
they couldn't be stapling	I couldn't have stapled
you couldn't have stapled
he couldn't have stapled
we couldn't have stapled
you couldn't have stapled
they couldn't have stapled	I couldn't have been stapling
you couldn't have been stapling
he couldn't have been stapling
we couldn't have been stapling
you couldn't have been stapling
they couldn't have been stapling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I staple?
could you staple?
could he staple?
could we staple?
could you staple?
could they staple? 	could I be stapling?
could you be stapling?
could he be stapling?
could we be stapling?
could you be stapling?
could they be stapling? 	could I have stapled?
could you have stapled?
could he have stapled?
could we have stapled?
could you have stapled?
could they have stapled? 	could I have been stapling?
could you have been stapling?
could he have been stapling?
could we have been stapling?
could you have been stapling?
could they have been stapling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I staple?
couldn't you staple?
couldn't he staple?
couldn't we staple?
couldn't you staple?
couldn't they staple? 	couldn't I be stapling?
couldn't you be stapling?
couldn't he be stapling?
couldn't we be stapling?
couldn't you be stapling?
couldn't they be stapling? 	couldn't I have stapled?
couldn't you have stapled?
couldn't he have stapled?
couldn't we have stapled?
couldn't you have stapled?
couldn't they have stapled? 	couldn't I have been stapling?
couldn't you have been stapling?
couldn't he have been stapling?
couldn't we have been stapling?
couldn't you have been stapling?
couldn't they have been stapling?