I could implement you could implement he could implement we could implement you could implement they could implement
V-ing form
I could be implementing you could be implementing he could be implementing we could be implementing you could be implementing they could be implementing
Perfect
I could have implemented you could have implemented he could have implemented we could have implemented you could have implemented they could have implemented
V-ing perfect
I could have been implementing you could have been implementing he could have been implementing we could have been implementing you could have been implementing they could have been implementing
Negation
Simple form
I couldn't implement you couldn't implement he couldn't implement we couldn't implement you couldn't implement they couldn't implement
V-ing form
I couldn't be implementing you couldn't be implementing he couldn't be implementing we couldn't be implementing you couldn't be implementing they couldn't be implementing
Perfect
I couldn't have implemented you couldn't have implemented he couldn't have implemented we couldn't have implemented you couldn't have implemented they couldn't have implemented
V-ing perfect
I couldn't have been implementing you couldn't have been implementing he couldn't have been implementing we couldn't have been implementing you couldn't have been implementing they couldn't have been implementing
Interrogative form
Simple form
could I implement? could you implement? could he implement? could we implement? could you implement? could they implement?
V-ing form
could I be implementing? could you be implementing? could he be implementing? could we be implementing? could you be implementing? could they be implementing?
Perfect
could I have implemented? could you have implemented? could he have implemented? could we have implemented? could you have implemented? could they have implemented?
V-ing perfect
could I have been implementing? could you have been implementing? could he have been implementing? could we have been implementing? could you have been implementing? could they have been implementing?
Interro-negative form
Simple form
couldn't I implement? couldn't you implement? couldn't he implement? couldn't we implement? couldn't you implement? couldn't they implement?
V-ing form
couldn't I be implementing? couldn't you be implementing? couldn't he be implementing? couldn't we be implementing? couldn't you be implementing? couldn't they be implementing?
Perfect
couldn't I have implemented? couldn't you have implemented? couldn't he have implemented? couldn't we have implemented? couldn't you have implemented? couldn't they have implemented?
V-ing perfect
couldn't I have been implementing? couldn't you have been implementing? couldn't he have been implementing? couldn't we have been implementing? couldn't you have been implementing? couldn't they have been implementing?