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