I could fitter you could fitter he could fitter we could fitter you could fitter they could fitter
V-ing form
I could be fittering you could be fittering he could be fittering we could be fittering you could be fittering they could be fittering
Perfect
I could have fittered you could have fittered he could have fittered we could have fittered you could have fittered they could have fittered
V-ing perfect
I could have been fittering you could have been fittering he could have been fittering we could have been fittering you could have been fittering they could have been fittering
Negation
Simple form
I could not fitter you could not fitter he could not fitter we could not fitter you could not fitter they could not fitter
V-ing form
I could not be fittering you could not be fittering he could not be fittering we could not be fittering you could not be fittering they could not be fittering
Perfect
I could not have fittered you could not have fittered he could not have fittered we could not have fittered you could not have fittered they could not have fittered
V-ing perfect
I could not have been fittering you could not have been fittering he could not have been fittering we could not have been fittering you could not have been fittering they could not have been fittering
Interrogative form
Simple form
could I fitter? could you fitter? could he fitter? could we fitter? could you fitter? could they fitter?
V-ing form
could I be fittering? could you be fittering? could he be fittering? could we be fittering? could you be fittering? could they be fittering?
Perfect
could I have fittered? could you have fittered? could he have fittered? could we have fittered? could you have fittered? could they have fittered?
V-ing perfect
could I have been fittering? could you have been fittering? could he have been fittering? could we have been fittering? could you have been fittering? could they have been fittering?
Interro-negative form
Simple form
could I not fitter? could you not fitter? could he not fitter? could we not fitter? could you not fitter? could they not fitter?
V-ing form
could I not be fittering? could you not be fittering? could he not be fittering? could we not be fittering? could you not be fittering? could they not be fittering?
Perfect
could I not have fittered? could you not have fittered? could he not have fittered? could we not have fittered? could you not have fittered? could they not have fittered?
V-ing perfect
could I not have been fittering? could you not have been fittering? could he not have been fittering? could we not have been fittering? could you not have been fittering? could they not have been fittering?