I could demonstrate you could demonstrate she could demonstrate we could demonstrate you could demonstrate they could demonstrate
V-ing form
I could be demonstrating you could be demonstrating she could be demonstrating we could be demonstrating you could be demonstrating they could be demonstrating
Perfect
I could have demonstrated you could have demonstrated she could have demonstrated we could have demonstrated you could have demonstrated they could have demonstrated
V-ing perfect
I could have been demonstrating you could have been demonstrating she could have been demonstrating we could have been demonstrating you could have been demonstrating they could have been demonstrating
Negation
Simple form
I could not demonstrate you could not demonstrate she could not demonstrate we could not demonstrate you could not demonstrate they could not demonstrate
V-ing form
I could not be demonstrating you could not be demonstrating she could not be demonstrating we could not be demonstrating you could not be demonstrating they could not be demonstrating
Perfect
I could not have demonstrated you could not have demonstrated she could not have demonstrated we could not have demonstrated you could not have demonstrated they could not have demonstrated
V-ing perfect
I could not have been demonstrating you could not have been demonstrating she could not have been demonstrating we could not have been demonstrating you could not have been demonstrating they could not have been demonstrating
Interrogative form
Simple form
could I demonstrate? could you demonstrate? could she demonstrate? could we demonstrate? could you demonstrate? could they demonstrate?
V-ing form
could I be demonstrating? could you be demonstrating? could she be demonstrating? could we be demonstrating? could you be demonstrating? could they be demonstrating?
Perfect
could I have demonstrated? could you have demonstrated? could she have demonstrated? could we have demonstrated? could you have demonstrated? could they have demonstrated?
V-ing perfect
could I have been demonstrating? could you have been demonstrating? could she have been demonstrating? could we have been demonstrating? could you have been demonstrating? could they have been demonstrating?
Interro-negative form
Simple form
could I not demonstrate? could you not demonstrate? could she not demonstrate? could we not demonstrate? could you not demonstrate? could they not demonstrate?
V-ing form
could I not be demonstrating? could you not be demonstrating? could she not be demonstrating? could we not be demonstrating? could you not be demonstrating? could they not be demonstrating?
Perfect
could I not have demonstrated? could you not have demonstrated? could she not have demonstrated? could we not have demonstrated? could you not have demonstrated? could they not have demonstrated?
V-ing perfect
could I not have been demonstrating? could you not have been demonstrating? could she not have been demonstrating? could we not have been demonstrating? could you not have been demonstrating? could they not have been demonstrating?