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