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