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