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