I can err you can err he can err we can err you can err they can err
V-ing form
I can be erring you can be erring he can be erring we can be erring you can be erring they can be erring
Perfect
I can have erred you can have erred he can have erred we can have erred you can have erred they can have erred
V-ing perfect
I can have been erring you can have been erring he can have been erring we can have been erring you can have been erring they can have been erring
Negation
Simple form
I can't err you can't err he can't err we can't err you can't err they can't err
V-ing form
I can't be erring you can't be erring he can't be erring we can't be erring you can't be erring they can't be erring
Perfect
I can't have erred you can't have erred he can't have erred we can't have erred you can't have erred they can't have erred
V-ing perfect
I can't have been erring you can't have been erring he can't have been erring we can't have been erring you can't have been erring they can't have been erring
Interrogative form
Simple form
can I err? can you err? can he err? can we err? can you err? can they err?
V-ing form
can I be erring? can you be erring? can he be erring? can we be erring? can you be erring? can they be erring?
Perfect
can I have erred? can you have erred? can he have erred? can we have erred? can you have erred? can they have erred?
V-ing perfect
can I have been erring? can you have been erring? can he have been erring? can we have been erring? can you have been erring? can they have been erring?
Interro-negative form
Simple form
can't I err? can't you err? can't he err? can't we err? can't you err? can't they err?
V-ing form
can't I be erring? can't you be erring? can't he be erring? can't we be erring? can't you be erring? can't they be erring?
Perfect
can't I have erred? can't you have erred? can't he have erred? can't we have erred? can't you have erred? can't they have erred?
V-ing perfect
can't I have been erring? can't you have been erring? can't he have been erring? can't we have been erring? can't you have been erring? can't they have been erring?