I could burn you could burn he could burn we could burn you could burn they could burn
V-ing form
I could be burning you could be burning he could be burning we could be burning you could be burning they could be burning
Perfect
I could have burned you could have burned he could have burned we could have burned you could have burned they could have burned
V-ing perfect
I could have been burning you could have been burning he could have been burning we could have been burning you could have been burning they could have been burning
Negation
Simple form
I couldn't burn you couldn't burn he couldn't burn we couldn't burn you couldn't burn they couldn't burn
V-ing form
I couldn't be burning you couldn't be burning he couldn't be burning we couldn't be burning you couldn't be burning they couldn't be burning
Perfect
I couldn't have burned you couldn't have burned he couldn't have burned we couldn't have burned you couldn't have burned they couldn't have burned
V-ing perfect
I couldn't have been burning you couldn't have been burning he couldn't have been burning we couldn't have been burning you couldn't have been burning they couldn't have been burning
Interrogative form
Simple form
could I burn? could you burn? could he burn? could we burn? could you burn? could they burn?
V-ing form
could I be burning? could you be burning? could he be burning? could we be burning? could you be burning? could they be burning?
Perfect
could I have burned? could you have burned? could he have burned? could we have burned? could you have burned? could they have burned?
V-ing perfect
could I have been burning? could you have been burning? could he have been burning? could we have been burning? could you have been burning? could they have been burning?
Interro-negative form
Simple form
couldn't I burn? couldn't you burn? couldn't he burn? couldn't we burn? couldn't you burn? couldn't they burn?
V-ing form
couldn't I be burning? couldn't you be burning? couldn't he be burning? couldn't we be burning? couldn't you be burning? couldn't they be burning?
Perfect
couldn't I have burned? couldn't you have burned? couldn't he have burned? couldn't we have burned? couldn't you have burned? couldn't they have burned?
V-ing perfect
couldn't I have been burning? couldn't you have been burning? couldn't he have been burning? couldn't we have been burning? couldn't you have been burning? couldn't they have been burning?