English verb conjugation
COULD UNDERSIGN

Regular verb: undersign - undersigned - undersigned

Affirmation

Simple form	V-ing form
I could undersign you could undersign she could undersign we could undersign you could undersign they could undersign	I could be undersigning you could be undersigning she could be undersigning we could be undersigning you could be undersigning they could be undersigning
Perfect	V-ing perfect
I could have undersigned you could have undersigned she could have undersigned we could have undersigned you could have undersigned they could have undersigned	I could have been undersigning you could have been undersigning she could have been undersigning we could have been undersigning you could have been undersigning they could have been undersigning

Negation

Simple form	V-ing form
I couldn't undersign you couldn't undersign she couldn't undersign we couldn't undersign you couldn't undersign they couldn't undersign	I couldn't be undersigning you couldn't be undersigning she couldn't be undersigning we couldn't be undersigning you couldn't be undersigning they couldn't be undersigning
Perfect	V-ing perfect
I couldn't have undersigned you couldn't have undersigned she couldn't have undersigned we couldn't have undersigned you couldn't have undersigned they couldn't have undersigned	I couldn't have been undersigning you couldn't have been undersigning she couldn't have been undersigning we couldn't have been undersigning you couldn't have been undersigning they couldn't have been undersigning

Interrogative form

Simple form	V-ing form
could I undersign? could you undersign? could she undersign? could we undersign? could you undersign? could they undersign?	could I be undersigning? could you be undersigning? could she be undersigning? could we be undersigning? could you be undersigning? could they be undersigning?
Perfect	V-ing perfect
could I have undersigned? could you have undersigned? could she have undersigned? could we have undersigned? could you have undersigned? could they have undersigned?	could I have been undersigning? could you have been undersigning? could she have been undersigning? could we have been undersigning? could you have been undersigning? could they have been undersigning?

Interro-negative form

Simple form	V-ing form
couldn't I undersign? couldn't you undersign? couldn't she undersign? couldn't we undersign? couldn't you undersign? couldn't they undersign?	couldn't I be undersigning? couldn't you be undersigning? couldn't she be undersigning? couldn't we be undersigning? couldn't you be undersigning? couldn't they be undersigning?
Perfect	V-ing perfect
couldn't I have undersigned? couldn't you have undersigned? couldn't she have undersigned? couldn't we have undersigned? couldn't you have undersigned? couldn't they have undersigned?	couldn't I have been undersigning? couldn't you have been undersigning? couldn't she have been undersigning? couldn't we have been undersigning? couldn't you have been undersigning? couldn't they have been undersigning?