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