I can litter you can litter he can litter we can litter you can litter they can litter
V-ing form
I can be littering you can be littering he can be littering we can be littering you can be littering they can be littering
Perfect
I can have littered you can have littered he can have littered we can have littered you can have littered they can have littered
V-ing perfect
I can have been littering you can have been littering he can have been littering we can have been littering you can have been littering they can have been littering
Negation
Simple form
I cannot litter you cannot litter he cannot litter we cannot litter you cannot litter they cannot litter
V-ing form
I cannot be littering you cannot be littering he cannot be littering we cannot be littering you cannot be littering they cannot be littering
Perfect
I cannot have littered you cannot have littered he cannot have littered we cannot have littered you cannot have littered they cannot have littered
V-ing perfect
I cannot have been littering you cannot have been littering he cannot have been littering we cannot have been littering you cannot have been littering they cannot have been littering
Interrogative form
Simple form
can I litter? can you litter? can he litter? can we litter? can you litter? can they litter?
V-ing form
can I be littering? can you be littering? can he be littering? can we be littering? can you be littering? can they be littering?
Perfect
can I have littered? can you have littered? can he have littered? can we have littered? can you have littered? can they have littered?
V-ing perfect
can I have been littering? can you have been littering? can he have been littering? can we have been littering? can you have been littering? can they have been littering?
Interro-negative form
Simple form
can I not litter? can you not litter? can he not litter? can we not litter? can you not litter? can they not litter?
V-ing form
can I not be littering? can you not be littering? can he not be littering? can we not be littering? can you not be littering? can they not be littering?
Perfect
can I not have littered? can you not have littered? can he not have littered? can we not have littered? can you not have littered? can they not have littered?
V-ing perfect
can I not have been littering? can you not have been littering? can he not have been littering? can we not have been littering? can you not have been littering? can they not have been littering?