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