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