I could top you could top he could top we could top you could top they could top
V-ing form
I could be topping you could be topping he could be topping we could be topping you could be topping they could be topping
Perfect
I could have topped you could have topped he could have topped we could have topped you could have topped they could have topped
V-ing perfect
I could have been topping you could have been topping he could have been topping we could have been topping you could have been topping they could have been topping
Negation
Simple form
I could not top you could not top he could not top we could not top you could not top they could not top
V-ing form
I could not be topping you could not be topping he could not be topping we could not be topping you could not be topping they could not be topping
Perfect
I could not have topped you could not have topped he could not have topped we could not have topped you could not have topped they could not have topped
V-ing perfect
I could not have been topping you could not have been topping he could not have been topping we could not have been topping you could not have been topping they could not have been topping
Interrogative form
Simple form
could I top? could you top? could he top? could we top? could you top? could they top?
V-ing form
could I be topping? could you be topping? could he be topping? could we be topping? could you be topping? could they be topping?
Perfect
could I have topped? could you have topped? could he have topped? could we have topped? could you have topped? could they have topped?
V-ing perfect
could I have been topping? could you have been topping? could he have been topping? could we have been topping? could you have been topping? could they have been topping?
Interro-negative form
Simple form
could I not top? could you not top? could he not top? could we not top? could you not top? could they not top?
V-ing form
could I not be topping? could you not be topping? could he not be topping? could we not be topping? could you not be topping? could they not be topping?
Perfect
could I not have topped? could you not have topped? could he not have topped? could we not have topped? could you not have topped? could they not have topped?
V-ing perfect
could I not have been topping? could you not have been topping? could he not have been topping? could we not have been topping? could you not have been topping? could they not have been topping?