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