I could heat you could heat he could heat we could heat you could heat they could heat
V-ing form
I could be heating you could be heating he could be heating we could be heating you could be heating they could be heating
Perfect
I could have heated you could have heated he could have heated we could have heated you could have heated they could have heated
V-ing perfect
I could have been heating you could have been heating he could have been heating we could have been heating you could have been heating they could have been heating
Negation
Simple form
I could not heat you could not heat he could not heat we could not heat you could not heat they could not heat
V-ing form
I could not be heating you could not be heating he could not be heating we could not be heating you could not be heating they could not be heating
Perfect
I could not have heated you could not have heated he could not have heated we could not have heated you could not have heated they could not have heated
V-ing perfect
I could not have been heating you could not have been heating he could not have been heating we could not have been heating you could not have been heating they could not have been heating
Interrogative form
Simple form
could I heat? could you heat? could he heat? could we heat? could you heat? could they heat?
V-ing form
could I be heating? could you be heating? could he be heating? could we be heating? could you be heating? could they be heating?
Perfect
could I have heated? could you have heated? could he have heated? could we have heated? could you have heated? could they have heated?
V-ing perfect
could I have been heating? could you have been heating? could he have been heating? could we have been heating? could you have been heating? could they have been heating?
Interro-negative form
Simple form
could I not heat? could you not heat? could he not heat? could we not heat? could you not heat? could they not heat?
V-ing form
could I not be heating? could you not be heating? could he not be heating? could we not be heating? could you not be heating? could they not be heating?
Perfect
could I not have heated? could you not have heated? could he not have heated? could we not have heated? could you not have heated? could they not have heated?
V-ing perfect
could I not have been heating? could you not have been heating? could he not have been heating? could we not have been heating? could you not have been heating? could they not have been heating?