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 could not staple
you could not staple
he could not staple
we could not staple
you could not staple
they could not staple 	I could not be stapling
you could not be stapling
he could not be stapling
we could not be stapling
you could not be stapling
they could not be stapling	I could not have stapled
you could not have stapled
he could not have stapled
we could not have stapled
you could not have stapled
they could not have stapled	I could not have been stapling
you could not have been stapling
he could not have been stapling
we could not have been stapling
you could not have been stapling
they could not 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 	
could I not staple?
could you not staple?
could he not staple?
could we not staple?
could you not staple?
could they not staple? 	could I not be stapling?
could you not be stapling?
could he not be stapling?
could we not be stapling?
could you not be stapling?
could they not be stapling? 	could I not have stapled?
could you not have stapled?
could he not have stapled?
could we not have stapled?
could you not have stapled?
could they not have stapled? 	could I not have been stapling?
could you not have been stapling?
could he not have been stapling?
could we not have been stapling?
could you not have been stapling?
could they not have been stapling?