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