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