I could extinguish you could extinguish he could extinguish we could extinguish you could extinguish they could extinguish
V-ing form
I could be extinguishing you could be extinguishing he could be extinguishing we could be extinguishing you could be extinguishing they could be extinguishing
Perfect
I could have extinguished you could have extinguished he could have extinguished we could have extinguished you could have extinguished they could have extinguished
V-ing perfect
I could have been extinguishing you could have been extinguishing he could have been extinguishing we could have been extinguishing you could have been extinguishing they could have been extinguishing
Negation
Simple form
I could not extinguish you could not extinguish he could not extinguish we could not extinguish you could not extinguish they could not extinguish
V-ing form
I could not be extinguishing you could not be extinguishing he could not be extinguishing we could not be extinguishing you could not be extinguishing they could not be extinguishing
Perfect
I could not have extinguished you could not have extinguished he could not have extinguished we could not have extinguished you could not have extinguished they could not have extinguished
V-ing perfect
I could not have been extinguishing you could not have been extinguishing he could not have been extinguishing we could not have been extinguishing you could not have been extinguishing they could not have been extinguishing
Interrogative form
Simple form
could I extinguish? could you extinguish? could he extinguish? could we extinguish? could you extinguish? could they extinguish?
V-ing form
could I be extinguishing? could you be extinguishing? could he be extinguishing? could we be extinguishing? could you be extinguishing? could they be extinguishing?
Perfect
could I have extinguished? could you have extinguished? could he have extinguished? could we have extinguished? could you have extinguished? could they have extinguished?
V-ing perfect
could I have been extinguishing? could you have been extinguishing? could he have been extinguishing? could we have been extinguishing? could you have been extinguishing? could they have been extinguishing?
Interro-negative form
Simple form
could I not extinguish? could you not extinguish? could he not extinguish? could we not extinguish? could you not extinguish? could they not extinguish?
V-ing form
could I not be extinguishing? could you not be extinguishing? could he not be extinguishing? could we not be extinguishing? could you not be extinguishing? could they not be extinguishing?
Perfect
could I not have extinguished? could you not have extinguished? could he not have extinguished? could we not have extinguished? could you not have extinguished? could they not have extinguished?
V-ing perfect
could I not have been extinguishing? could you not have been extinguishing? could he not have been extinguishing? could we not have been extinguishing? could you not have been extinguishing? could they not have been extinguishing?