I can head you can head she can head we can head you can head they can head
V-ing form
I can be heading you can be heading she can be heading we can be heading you can be heading they can be heading
Perfect
I can have headed you can have headed she can have headed we can have headed you can have headed they can have headed
V-ing perfect
I can have been heading you can have been heading she can have been heading we can have been heading you can have been heading they can have been heading
Negation
Simple form
I cannot head you cannot head she cannot head we cannot head you cannot head they cannot head
V-ing form
I cannot be heading you cannot be heading she cannot be heading we cannot be heading you cannot be heading they cannot be heading
Perfect
I cannot have headed you cannot have headed she cannot have headed we cannot have headed you cannot have headed they cannot have headed
V-ing perfect
I cannot have been heading you cannot have been heading she cannot have been heading we cannot have been heading you cannot have been heading they cannot have been heading
Interrogative form
Simple form
can I head? can you head? can she head? can we head? can you head? can they head?
V-ing form
can I be heading? can you be heading? can she be heading? can we be heading? can you be heading? can they be heading?
Perfect
can I have headed? can you have headed? can she have headed? can we have headed? can you have headed? can they have headed?
V-ing perfect
can I have been heading? can you have been heading? can she have been heading? can we have been heading? can you have been heading? can they have been heading?
Interro-negative form
Simple form
can I not head? can you not head? can she not head? can we not head? can you not head? can they not head?
V-ing form
can I not be heading? can you not be heading? can she not be heading? can we not be heading? can you not be heading? can they not be heading?
Perfect
can I not have headed? can you not have headed? can she not have headed? can we not have headed? can you not have headed? can they not have headed?
V-ing perfect
can I not have been heading? can you not have been heading? can she not have been heading? can we not have been heading? can you not have been heading? can they not have been heading?