I can itch you can itch he can itch we can itch you can itch they can itch
V-ing form
I can be itching you can be itching he can be itching we can be itching you can be itching they can be itching
Perfect
I can have itched you can have itched he can have itched we can have itched you can have itched they can have itched
V-ing perfect
I can have been itching you can have been itching he can have been itching we can have been itching you can have been itching they can have been itching
Negation
Simple form
I can't itch you can't itch he can't itch we can't itch you can't itch they can't itch
V-ing form
I can't be itching you can't be itching he can't be itching we can't be itching you can't be itching they can't be itching
Perfect
I can't have itched you can't have itched he can't have itched we can't have itched you can't have itched they can't have itched
V-ing perfect
I can't have been itching you can't have been itching he can't have been itching we can't have been itching you can't have been itching they can't have been itching
Interrogative form
Simple form
can I itch? can you itch? can he itch? can we itch? can you itch? can they itch?
V-ing form
can I be itching? can you be itching? can he be itching? can we be itching? can you be itching? can they be itching?
Perfect
can I have itched? can you have itched? can he have itched? can we have itched? can you have itched? can they have itched?
V-ing perfect
can I have been itching? can you have been itching? can he have been itching? can we have been itching? can you have been itching? can they have been itching?
Interro-negative form
Simple form
can't I itch? can't you itch? can't he itch? can't we itch? can't you itch? can't they itch?
V-ing form
can't I be itching? can't you be itching? can't he be itching? can't we be itching? can't you be itching? can't they be itching?
Perfect
can't I have itched? can't you have itched? can't he have itched? can't we have itched? can't you have itched? can't they have itched?
V-ing perfect
can't I have been itching? can't you have been itching? can't he have been itching? can't we have been itching? can't you have been itching? can't they have been itching?