I could extemporize you could extemporize he could extemporize we could extemporize you could extemporize they could extemporize
V-ing form
I could be extemporizing you could be extemporizing he could be extemporizing we could be extemporizing you could be extemporizing they could be extemporizing
Perfect
I could have extemporized you could have extemporized he could have extemporized we could have extemporized you could have extemporized they could have extemporized
V-ing perfect
I could have been extemporizing you could have been extemporizing he could have been extemporizing we could have been extemporizing you could have been extemporizing they could have been extemporizing
Negation
Simple form
I could not extemporize you could not extemporize he could not extemporize we could not extemporize you could not extemporize they could not extemporize
V-ing form
I could not be extemporizing you could not be extemporizing he could not be extemporizing we could not be extemporizing you could not be extemporizing they could not be extemporizing
Perfect
I could not have extemporized you could not have extemporized he could not have extemporized we could not have extemporized you could not have extemporized they could not have extemporized
V-ing perfect
I could not have been extemporizing you could not have been extemporizing he could not have been extemporizing we could not have been extemporizing you could not have been extemporizing they could not have been extemporizing
Interrogative form
Simple form
could I extemporize? could you extemporize? could he extemporize? could we extemporize? could you extemporize? could they extemporize?
V-ing form
could I be extemporizing? could you be extemporizing? could he be extemporizing? could we be extemporizing? could you be extemporizing? could they be extemporizing?
Perfect
could I have extemporized? could you have extemporized? could he have extemporized? could we have extemporized? could you have extemporized? could they have extemporized?
V-ing perfect
could I have been extemporizing? could you have been extemporizing? could he have been extemporizing? could we have been extemporizing? could you have been extemporizing? could they have been extemporizing?
Interro-negative form
Simple form
could I not extemporize? could you not extemporize? could he not extemporize? could we not extemporize? could you not extemporize? could they not extemporize?
V-ing form
could I not be extemporizing? could you not be extemporizing? could he not be extemporizing? could we not be extemporizing? could you not be extemporizing? could they not be extemporizing?
Perfect
could I not have extemporized? could you not have extemporized? could he not have extemporized? could we not have extemporized? could you not have extemporized? could they not have extemporized?
V-ing perfect
could I not have been extemporizing? could you not have been extemporizing? could he not have been extemporizing? could we not have been extemporizing? could you not have been extemporizing? could they not have been extemporizing?