I could cement you could cement he could cement we could cement you could cement they could cement
V-ing form
I could be cementing you could be cementing he could be cementing we could be cementing you could be cementing they could be cementing
Perfect
I could have cemented you could have cemented he could have cemented we could have cemented you could have cemented they could have cemented
V-ing perfect
I could have been cementing you could have been cementing he could have been cementing we could have been cementing you could have been cementing they could have been cementing
Negation
Simple form
I could not cement you could not cement he could not cement we could not cement you could not cement they could not cement
V-ing form
I could not be cementing you could not be cementing he could not be cementing we could not be cementing you could not be cementing they could not be cementing
Perfect
I could not have cemented you could not have cemented he could not have cemented we could not have cemented you could not have cemented they could not have cemented
V-ing perfect
I could not have been cementing you could not have been cementing he could not have been cementing we could not have been cementing you could not have been cementing they could not have been cementing
Interrogative form
Simple form
could I cement? could you cement? could he cement? could we cement? could you cement? could they cement?
V-ing form
could I be cementing? could you be cementing? could he be cementing? could we be cementing? could you be cementing? could they be cementing?
Perfect
could I have cemented? could you have cemented? could he have cemented? could we have cemented? could you have cemented? could they have cemented?
V-ing perfect
could I have been cementing? could you have been cementing? could he have been cementing? could we have been cementing? could you have been cementing? could they have been cementing?
Interro-negative form
Simple form
could I not cement? could you not cement? could he not cement? could we not cement? could you not cement? could they not cement?
V-ing form
could I not be cementing? could you not be cementing? could he not be cementing? could we not be cementing? could you not be cementing? could they not be cementing?
Perfect
could I not have cemented? could you not have cemented? could he not have cemented? could we not have cemented? could you not have cemented? could they not have cemented?
V-ing perfect
could I not have been cementing? could you not have been cementing? could he not have been cementing? could we not have been cementing? could you not have been cementing? could they not have been cementing?