I could complete you could complete she could complete we could complete you could complete they could complete
V-ing form
I could be completing you could be completing she could be completing we could be completing you could be completing they could be completing
Perfect
I could have completed you could have completed she could have completed we could have completed you could have completed they could have completed
V-ing perfect
I could have been completing you could have been completing she could have been completing we could have been completing you could have been completing they could have been completing
Negation
Simple form
I could not complete you could not complete she could not complete we could not complete you could not complete they could not complete
V-ing form
I could not be completing you could not be completing she could not be completing we could not be completing you could not be completing they could not be completing
Perfect
I could not have completed you could not have completed she could not have completed we could not have completed you could not have completed they could not have completed
V-ing perfect
I could not have been completing you could not have been completing she could not have been completing we could not have been completing you could not have been completing they could not have been completing
Interrogative form
Simple form
could I complete? could you complete? could she complete? could we complete? could you complete? could they complete?
V-ing form
could I be completing? could you be completing? could she be completing? could we be completing? could you be completing? could they be completing?
Perfect
could I have completed? could you have completed? could she have completed? could we have completed? could you have completed? could they have completed?
V-ing perfect
could I have been completing? could you have been completing? could she have been completing? could we have been completing? could you have been completing? could they have been completing?
Interro-negative form
Simple form
could I not complete? could you not complete? could she not complete? could we not complete? could you not complete? could they not complete?
V-ing form
could I not be completing? could you not be completing? could she not be completing? could we not be completing? could you not be completing? could they not be completing?
Perfect
could I not have completed? could you not have completed? could she not have completed? could we not have completed? could you not have completed? could they not have completed?
V-ing perfect
could I not have been completing? could you not have been completing? could she not have been completing? could we not have been completing? could you not have been completing? could they not have been completing?