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