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