I could extemporise you could extemporise he could extemporise we could extemporise you could extemporise they could extemporise
V-ing form
I could be extemporising you could be extemporising he could be extemporising we could be extemporising you could be extemporising they could be extemporising
Perfect
I could have extemporised you could have extemporised he could have extemporised we could have extemporised you could have extemporised they could have extemporised
V-ing perfect
I could have been extemporising you could have been extemporising he could have been extemporising we could have been extemporising you could have been extemporising they could have been extemporising
Negation
Simple form
I could not extemporise you could not extemporise he could not extemporise we could not extemporise you could not extemporise they could not extemporise
V-ing form
I could not be extemporising you could not be extemporising he could not be extemporising we could not be extemporising you could not be extemporising they could not be extemporising
Perfect
I could not have extemporised you could not have extemporised he could not have extemporised we could not have extemporised you could not have extemporised they could not have extemporised
V-ing perfect
I could not have been extemporising you could not have been extemporising he could not have been extemporising we could not have been extemporising you could not have been extemporising they could not have been extemporising
Interrogative form
Simple form
could I extemporise? could you extemporise? could he extemporise? could we extemporise? could you extemporise? could they extemporise?
V-ing form
could I be extemporising? could you be extemporising? could he be extemporising? could we be extemporising? could you be extemporising? could they be extemporising?
Perfect
could I have extemporised? could you have extemporised? could he have extemporised? could we have extemporised? could you have extemporised? could they have extemporised?
V-ing perfect
could I have been extemporising? could you have been extemporising? could he have been extemporising? could we have been extemporising? could you have been extemporising? could they have been extemporising?
Interro-negative form
Simple form
could I not extemporise? could you not extemporise? could he not extemporise? could we not extemporise? could you not extemporise? could they not extemporise?
V-ing form
could I not be extemporising? could you not be extemporising? could he not be extemporising? could we not be extemporising? could you not be extemporising? could they not be extemporising?
Perfect
could I not have extemporised? could you not have extemporised? could he not have extemporised? could we not have extemporised? could you not have extemporised? could they not have extemporised?
V-ing perfect
could I not have been extemporising? could you not have been extemporising? could he not have been extemporising? could we not have been extemporising? could you not have been extemporising? could they not have been extemporising?