I could head you could head she could head we could head you could head they could head
V-ing form
I could be heading you could be heading she could be heading we could be heading you could be heading they could be heading
Perfect
I could have headed you could have headed she could have headed we could have headed you could have headed they could have headed
V-ing perfect
I could have been heading you could have been heading she could have been heading we could have been heading you could have been heading they could have been heading
Negation
Simple form
I couldn't head you couldn't head she couldn't head we couldn't head you couldn't head they couldn't head
V-ing form
I couldn't be heading you couldn't be heading she couldn't be heading we couldn't be heading you couldn't be heading they couldn't be heading
Perfect
I couldn't have headed you couldn't have headed she couldn't have headed we couldn't have headed you couldn't have headed they couldn't have headed
V-ing perfect
I couldn't have been heading you couldn't have been heading she couldn't have been heading we couldn't have been heading you couldn't have been heading they couldn't have been heading
Interrogative form
Simple form
could I head? could you head? could she head? could we head? could you head? could they head?
V-ing form
could I be heading? could you be heading? could she be heading? could we be heading? could you be heading? could they be heading?
Perfect
could I have headed? could you have headed? could she have headed? could we have headed? could you have headed? could they have headed?
V-ing perfect
could I have been heading? could you have been heading? could she have been heading? could we have been heading? could you have been heading? could they have been heading?
Interro-negative form
Simple form
couldn't I head? couldn't you head? couldn't she head? couldn't we head? couldn't you head? couldn't they head?
V-ing form
couldn't I be heading? couldn't you be heading? couldn't she be heading? couldn't we be heading? couldn't you be heading? couldn't they be heading?
Perfect
couldn't I have headed? couldn't you have headed? couldn't she have headed? couldn't we have headed? couldn't you have headed? couldn't they have headed?
V-ing perfect
couldn't I have been heading? couldn't you have been heading? couldn't she have been heading? couldn't we have been heading? couldn't you have been heading? couldn't they have been heading?