could retrieve
Regular verb: retrieve - retrieved- retrieved

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could retrieve
you could retrieve
she could retrieve
we could retrieve
you could retrieve
they could retrieve 	I could be retrieving
you could be retrieving
she could be retrieving
we could be retrieving
you could be retrieving
they could be retrieving	I could have retrieved
you could have retrieved
she could have retrieved
we could have retrieved
you could have retrieved
they could have retrieved	I could have been retrieving
you could have been retrieving
she could have been retrieving
we could have been retrieving
you could have been retrieving
they could have been retrieving	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't retrieve
you couldn't retrieve
she couldn't retrieve
we couldn't retrieve
you couldn't retrieve
they couldn't retrieve 	I couldn't be retrieving
you couldn't be retrieving
she couldn't be retrieving
we couldn't be retrieving
you couldn't be retrieving
they couldn't be retrieving	I couldn't have retrieved
you couldn't have retrieved
she couldn't have retrieved
we couldn't have retrieved
you couldn't have retrieved
they couldn't have retrieved	I couldn't have been retrieving
you couldn't have been retrieving
she couldn't have been retrieving
we couldn't have been retrieving
you couldn't have been retrieving
they couldn't have been retrieving	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I retrieve?
could you retrieve?
could she retrieve?
could we retrieve?
could you retrieve?
could they retrieve? 	could I be retrieving?
could you be retrieving?
could she be retrieving?
could we be retrieving?
could you be retrieving?
could they be retrieving? 	could I have retrieved?
could you have retrieved?
could she have retrieved?
could we have retrieved?
could you have retrieved?
could they have retrieved? 	could I have been retrieving?
could you have been retrieving?
could she have been retrieving?
could we have been retrieving?
could you have been retrieving?
could they have been retrieving? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I retrieve?
couldn't you retrieve?
couldn't she retrieve?
couldn't we retrieve?
couldn't you retrieve?
couldn't they retrieve? 	couldn't I be retrieving?
couldn't you be retrieving?
couldn't she be retrieving?
couldn't we be retrieving?
couldn't you be retrieving?
couldn't they be retrieving? 	couldn't I have retrieved?
couldn't you have retrieved?
couldn't she have retrieved?
couldn't we have retrieved?
couldn't you have retrieved?
couldn't they have retrieved? 	couldn't I have been retrieving?
couldn't you have been retrieving?
couldn't she have been retrieving?
couldn't we have been retrieving?
couldn't you have been retrieving?
couldn't they have been retrieving?