English verb conjugation
CAN UNDERSIGN

Regular verb: undersign - undersigned - undersigned

Affirmation

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

Negation

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

Interrogative form

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

Interro-negative form

Simple form	V-ing form
can I not undersign? can you not undersign? can she not undersign? can we not undersign? can you not undersign? can they not undersign?	can I not be undersigning? can you not be undersigning? can she not be undersigning? can we not be undersigning? can you not be undersigning? can they not be undersigning?
Perfect	V-ing perfect
can I not have undersigned? can you not have undersigned? can she not have undersigned? can we not have undersigned? can you not have undersigned? can they not have undersigned?	can I not have been undersigning? can you not have been undersigning? can she not have been undersigning? can we not have been undersigning? can you not have been undersigning? can they not have been undersigning?