I could litter you could litter he could litter we could litter you could litter they could litter
Forma com V-ing
I could be littering you could be littering he could be littering we could be littering you could be littering they could be littering
Perfeito
I could have littered you could have littered he could have littered we could have littered you could have littered they could have littered
Perfeito com V-ing
I could have been littering you could have been littering he could have been littering we could have been littering you could have been littering they could have been littering
Negação
Forma simple
I could not litter you could not litter he could not litter we could not litter you could not litter they could not litter
Forma com V-ing
I could not be littering you could not be littering he could not be littering we could not be littering you could not be littering they could not be littering
Perfeito
I could not have littered you could not have littered he could not have littered we could not have littered you could not have littered they could not have littered
Perfeito com V-ing
I could not have been littering you could not have been littering he could not have been littering we could not have been littering you could not have been littering they could not have been littering
Forma interrogativa
Forma simple
could I litter? could you litter? could he litter? could we litter? could you litter? could they litter?
Forma com V-ing
could I be littering? could you be littering? could he be littering? could we be littering? could you be littering? could they be littering?
Perfeito
could I have littered? could you have littered? could he have littered? could we have littered? could you have littered? could they have littered?
Perfeito com V-ing
could I have been littering? could you have been littering? could he have been littering? could we have been littering? could you have been littering? could they have been littering?
Forma interro-Negação
Forma simple
could I not litter? could you not litter? could he not litter? could we not litter? could you not litter? could they not litter?
Forma com V-ing
could I not be littering? could you not be littering? could he not be littering? could we not be littering? could you not be littering? could they not be littering?
Perfeito
could I not have littered? could you not have littered? could he not have littered? could we not have littered? could you not have littered? could they not have littered?
Perfeito com V-ing
could I not have been littering? could you not have been littering? could he not have been littering? could we not have been littering? could you not have been littering? could they not have been littering?