English verb conjugation
COULD RETRIEVE

Regular verb: retrieve - retrieved - retrieved

Affirmation

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