I could landmark you could landmark she could landmark we could landmark you could landmark they could landmark
V-ing form
I could be landmarking you could be landmarking she could be landmarking we could be landmarking you could be landmarking they could be landmarking
Perfect
I could have landmarked you could have landmarked she could have landmarked we could have landmarked you could have landmarked they could have landmarked
V-ing perfect
I could have been landmarking you could have been landmarking she could have been landmarking we could have been landmarking you could have been landmarking they could have been landmarking
Negation
Simple form
I could not landmark you could not landmark she could not landmark we could not landmark you could not landmark they could not landmark
V-ing form
I could not be landmarking you could not be landmarking she could not be landmarking we could not be landmarking you could not be landmarking they could not be landmarking
Perfect
I could not have landmarked you could not have landmarked she could not have landmarked we could not have landmarked you could not have landmarked they could not have landmarked
V-ing perfect
I could not have been landmarking you could not have been landmarking she could not have been landmarking we could not have been landmarking you could not have been landmarking they could not have been landmarking
Interrogative form
Simple form
could I landmark? could you landmark? could she landmark? could we landmark? could you landmark? could they landmark?
V-ing form
could I be landmarking? could you be landmarking? could she be landmarking? could we be landmarking? could you be landmarking? could they be landmarking?
Perfect
could I have landmarked? could you have landmarked? could she have landmarked? could we have landmarked? could you have landmarked? could they have landmarked?
V-ing perfect
could I have been landmarking? could you have been landmarking? could she have been landmarking? could we have been landmarking? could you have been landmarking? could they have been landmarking?
Interro-negative form
Simple form
could I not landmark? could you not landmark? could she not landmark? could we not landmark? could you not landmark? could they not landmark?
V-ing form
could I not be landmarking? could you not be landmarking? could she not be landmarking? could we not be landmarking? could you not be landmarking? could they not be landmarking?
Perfect
could I not have landmarked? could you not have landmarked? could she not have landmarked? could we not have landmarked? could you not have landmarked? could they not have landmarked?
V-ing perfect
could I not have been landmarking? could you not have been landmarking? could she not have been landmarking? could we not have been landmarking? could you not have been landmarking? could they not have been landmarking?