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 can't litter you can't litter he can't litter we can't litter you can't litter they can't litter
V-ing form
I can't be littering you can't be littering he can't be littering we can't be littering you can't be littering they can't be littering
Perfect
I can't have littered you can't have littered he can't have littered we can't have littered you can't have littered they can't have littered
V-ing perfect
I can't have been littering you can't have been littering he can't have been littering we can't have been littering you can't have been littering they can't 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't I litter? can't you litter? can't he litter? can't we litter? can't you litter? can't they litter?
V-ing form
can't I be littering? can't you be littering? can't he be littering? can't we be littering? can't you be littering? can't they be littering?
Perfect
can't I have littered? can't you have littered? can't he have littered? can't we have littered? can't you have littered? can't they have littered?
V-ing perfect
can't I have been littering? can't you have been littering? can't he have been littering? can't we have been littering? can't you have been littering? can't they have been littering?