I can tough you can tough he can tough we can tough you can tough they can tough
V-ing form
I can be toughing you can be toughing he can be toughing we can be toughing you can be toughing they can be toughing
Perfect
I can have toughed you can have toughed he can have toughed we can have toughed you can have toughed they can have toughed
V-ing perfect
I can have been toughing you can have been toughing he can have been toughing we can have been toughing you can have been toughing they can have been toughing
Negation
Simple form
I can't tough you can't tough he can't tough we can't tough you can't tough they can't tough
V-ing form
I can't be toughing you can't be toughing he can't be toughing we can't be toughing you can't be toughing they can't be toughing
Perfect
I can't have toughed you can't have toughed he can't have toughed we can't have toughed you can't have toughed they can't have toughed
V-ing perfect
I can't have been toughing you can't have been toughing he can't have been toughing we can't have been toughing you can't have been toughing they can't have been toughing
Interrogative form
Simple form
can I tough? can you tough? can he tough? can we tough? can you tough? can they tough?
V-ing form
can I be toughing? can you be toughing? can he be toughing? can we be toughing? can you be toughing? can they be toughing?
Perfect
can I have toughed? can you have toughed? can he have toughed? can we have toughed? can you have toughed? can they have toughed?
V-ing perfect
can I have been toughing? can you have been toughing? can he have been toughing? can we have been toughing? can you have been toughing? can they have been toughing?
Interro-negative form
Simple form
can't I tough? can't you tough? can't he tough? can't we tough? can't you tough? can't they tough?
V-ing form
can't I be toughing? can't you be toughing? can't he be toughing? can't we be toughing? can't you be toughing? can't they be toughing?
Perfect
can't I have toughed? can't you have toughed? can't he have toughed? can't we have toughed? can't you have toughed? can't they have toughed?
V-ing perfect
can't I have been toughing? can't you have been toughing? can't he have been toughing? can't we have been toughing? can't you have been toughing? can't they have been toughing?