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