English verb conjugation
MUST COUNTERSIGN

Regular verb: countersign - countersigned - countersigned

Affirmation

Simple form	V-ing form
I must countersign you must countersign she must countersign we must countersign you must countersign they must countersign	I must be countersigning you must be countersigning she must be countersigning we must be countersigning you must be countersigning they must be countersigning
Perfect	V-ing perfect
I must have countersigned you must have countersigned she must have countersigned we must have countersigned you must have countersigned they must have countersigned	I must have been countersigning you must have been countersigning she must have been countersigning we must have been countersigning you must have been countersigning they must have been countersigning

Negation

Simple form	V-ing form
I mustn't countersign you mustn't countersign she mustn't countersign we mustn't countersign you mustn't countersign they mustn't countersign	I mustn't be countersigning you mustn't be countersigning she mustn't be countersigning we mustn't be countersigning you mustn't be countersigning they mustn't be countersigning
Perfect	V-ing perfect
I mustn't have countersigned you mustn't have countersigned she mustn't have countersigned we mustn't have countersigned you mustn't have countersigned they mustn't have countersigned	I mustn't have been countersigning you mustn't have been countersigning she mustn't have been countersigning we mustn't have been countersigning you mustn't have been countersigning they mustn't have been countersigning

Interrogative form

Simple form	V-ing form
must I countersign? must you countersign? must she countersign? must we countersign? must you countersign? must they countersign?	must I be countersigning? must you be countersigning? must she be countersigning? must we be countersigning? must you be countersigning? must they be countersigning?
Perfect	V-ing perfect
must I have countersigned? must you have countersigned? must she have countersigned? must we have countersigned? must you have countersigned? must they have countersigned?	must I have been countersigning? must you have been countersigning? must she have been countersigning? must we have been countersigning? must you have been countersigning? must they have been countersigning?

Interro-negative form

Simple form	V-ing form
mustn't I countersign? mustn't you countersign? mustn't she countersign? mustn't we countersign? mustn't you countersign? mustn't they countersign?	mustn't I be countersigning? mustn't you be countersigning? mustn't she be countersigning? mustn't we be countersigning? mustn't you be countersigning? mustn't they be countersigning?
Perfect	V-ing perfect
mustn't I have countersigned? mustn't you have countersigned? mustn't she have countersigned? mustn't we have countersigned? mustn't you have countersigned? mustn't they have countersigned?	mustn't I have been countersigning? mustn't you have been countersigning? mustn't she have been countersigning? mustn't we have been countersigning? mustn't you have been countersigning? mustn't they have been countersigning?