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