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 couldn't extemporise you couldn't extemporise he couldn't extemporise we couldn't extemporise you couldn't extemporise they couldn't extemporise
V-ing form
I couldn't be extemporising you couldn't be extemporising he couldn't be extemporising we couldn't be extemporising you couldn't be extemporising they couldn't be extemporising
Perfect
I couldn't have extemporised you couldn't have extemporised he couldn't have extemporised we couldn't have extemporised you couldn't have extemporised they couldn't have extemporised
V-ing perfect
I couldn't have been extemporising you couldn't have been extemporising he couldn't have been extemporising we couldn't have been extemporising you couldn't have been extemporising they couldn't 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
couldn't I extemporise? couldn't you extemporise? couldn't he extemporise? couldn't we extemporise? couldn't you extemporise? couldn't they extemporise?
V-ing form
couldn't I be extemporising? couldn't you be extemporising? couldn't he be extemporising? couldn't we be extemporising? couldn't you be extemporising? couldn't they be extemporising?
Perfect
couldn't I have extemporised? couldn't you have extemporised? couldn't he have extemporised? couldn't we have extemporised? couldn't you have extemporised? couldn't they have extemporised?
V-ing perfect
couldn't I have been extemporising? couldn't you have been extemporising? couldn't he have been extemporising? couldn't we have been extemporising? couldn't you have been extemporising? couldn't they have been extemporising?