I could attend you could attend she could attend we could attend you could attend they could attend
V-ing form
I could be attending you could be attending she could be attending we could be attending you could be attending they could be attending
Perfect
I could have attended you could have attended she could have attended we could have attended you could have attended they could have attended
V-ing perfect
I could have been attending you could have been attending she could have been attending we could have been attending you could have been attending they could have been attending
Negation
Simple form
I couldn't attend you couldn't attend she couldn't attend we couldn't attend you couldn't attend they couldn't attend
V-ing form
I couldn't be attending you couldn't be attending she couldn't be attending we couldn't be attending you couldn't be attending they couldn't be attending
Perfect
I couldn't have attended you couldn't have attended she couldn't have attended we couldn't have attended you couldn't have attended they couldn't have attended
V-ing perfect
I couldn't have been attending you couldn't have been attending she couldn't have been attending we couldn't have been attending you couldn't have been attending they couldn't have been attending
Interrogative form
Simple form
could I attend? could you attend? could she attend? could we attend? could you attend? could they attend?
V-ing form
could I be attending? could you be attending? could she be attending? could we be attending? could you be attending? could they be attending?
Perfect
could I have attended? could you have attended? could she have attended? could we have attended? could you have attended? could they have attended?
V-ing perfect
could I have been attending? could you have been attending? could she have been attending? could we have been attending? could you have been attending? could they have been attending?
Interro-negative form
Simple form
couldn't I attend? couldn't you attend? couldn't she attend? couldn't we attend? couldn't you attend? couldn't they attend?
V-ing form
couldn't I be attending? couldn't you be attending? couldn't she be attending? couldn't we be attending? couldn't you be attending? couldn't they be attending?
Perfect
couldn't I have attended? couldn't you have attended? couldn't she have attended? couldn't we have attended? couldn't you have attended? couldn't they have attended?
V-ing perfect
couldn't I have been attending? couldn't you have been attending? couldn't she have been attending? couldn't we have been attending? couldn't you have been attending? couldn't they have been attending?