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