I could burl you could burl she could burl we could burl you could burl they could burl
V-ing form
I could be burling you could be burling she could be burling we could be burling you could be burling they could be burling
Perfect
I could have burled you could have burled she could have burled we could have burled you could have burled they could have burled
V-ing perfect
I could have been burling you could have been burling she could have been burling we could have been burling you could have been burling they could have been burling
Negation
Simple form
I could not burl you could not burl she could not burl we could not burl you could not burl they could not burl
V-ing form
I could not be burling you could not be burling she could not be burling we could not be burling you could not be burling they could not be burling
Perfect
I could not have burled you could not have burled she could not have burled we could not have burled you could not have burled they could not have burled
V-ing perfect
I could not have been burling you could not have been burling she could not have been burling we could not have been burling you could not have been burling they could not have been burling
Interrogative form
Simple form
could I burl? could you burl? could she burl? could we burl? could you burl? could they burl?
V-ing form
could I be burling? could you be burling? could she be burling? could we be burling? could you be burling? could they be burling?
Perfect
could I have burled? could you have burled? could she have burled? could we have burled? could you have burled? could they have burled?
V-ing perfect
could I have been burling? could you have been burling? could she have been burling? could we have been burling? could you have been burling? could they have been burling?
Interro-negative form
Simple form
could I not burl? could you not burl? could she not burl? could we not burl? could you not burl? could they not burl?
V-ing form
could I not be burling? could you not be burling? could she not be burling? could we not be burling? could you not be burling? could they not be burling?
Perfect
could I not have burled? could you not have burled? could she not have burled? could we not have burled? could you not have burled? could they not have burled?
V-ing perfect
could I not have been burling? could you not have been burling? could she not have been burling? could we not have been burling? could you not have been burling? could they not have been burling?