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