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