I can itch you can itch she can itch we can itch you can itch they can itch
V-ing form
I can be itching you can be itching she can be itching we can be itching you can be itching they can be itching
Perfect
I can have itched you can have itched she 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 she can have been itching we can have been itching you can have been itching they can have been itching
Negation
Simple form
I cannot itch you cannot itch she cannot itch we cannot itch you cannot itch they cannot itch
V-ing form
I cannot be itching you cannot be itching she cannot be itching we cannot be itching you cannot be itching they cannot be itching
Perfect
I cannot have itched you cannot have itched she cannot have itched we cannot have itched you cannot have itched they cannot have itched
V-ing perfect
I cannot have been itching you cannot have been itching she cannot have been itching we cannot have been itching you cannot have been itching they cannot have been itching
Interrogative form
Simple form
can I itch? can you itch? can she itch? can we itch? can you itch? can they itch?
V-ing form
can I be itching? can you be itching? can she be itching? can we be itching? can you be itching? can they be itching?
Perfect
can I have itched? can you have itched? can she 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 she have been itching? can we have been itching? can you have been itching? can they have been itching?
Interro-negative form
Simple form
can I not itch? can you not itch? can she not itch? can we not itch? can you not itch? can they not itch?
V-ing form
can I not be itching? can you not be itching? can she not be itching? can we not be itching? can you not be itching? can they not be itching?
Perfect
can I not have itched? can you not have itched? can she not have itched? can we not have itched? can you not have itched? can they not have itched?
V-ing perfect
can I not have been itching? can you not have been itching? can she not have been itching? can we not have been itching? can you not have been itching? can they not have been itching?