I'll be littering you'll be littering he'll be littering we'll be littering you'll be littering they'll be littering
Future perfect
I'll have littered you'll have littered he'll have littered we'll have littered you'll have littered they'll have littered
Future perfect continuous
I'll have been littering you'll have been littering he'll have been littering we'll have been littering you'll have been littering they'll have been littering
I'd be littering you'd be littering he'd be littering we'd be littering you'd be littering they'd be littering
Past
I'd have littered you'd have littered he'd have littered we'd have littered you'd have littered they'd have littered
Past continuous
I'd have been littering you'd have been littering he'd have been littering we'd have been littering you'd have been littering they'd have been littering