I must countersign you must countersign he must countersign we must countersign you must countersign they must countersign
V-ing form
I must be countersigning you must be countersigning he must be countersigning we must be countersigning you must be countersigning they must be countersigning
Perfect
I must have countersigned you must have countersigned he must have countersigned we must have countersigned you must have countersigned they must have countersigned
V-ing perfect
I must have been countersigning you must have been countersigning he must have been countersigning we must have been countersigning you must have been countersigning they must have been countersigning
Negation
Simple form
I mustn't countersign you mustn't countersign he mustn't countersign we mustn't countersign you mustn't countersign they mustn't countersign
V-ing form
I mustn't be countersigning you mustn't be countersigning he mustn't be countersigning we mustn't be countersigning you mustn't be countersigning they mustn't be countersigning
Perfect
I mustn't have countersigned you mustn't have countersigned he mustn't have countersigned we mustn't have countersigned you mustn't have countersigned they mustn't have countersigned
V-ing perfect
I mustn't have been countersigning you mustn't have been countersigning he 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
must I countersign? must you countersign? must he countersign? must we countersign? must you countersign? must they countersign?
V-ing form
must I be countersigning? must you be countersigning? must he be countersigning? must we be countersigning? must you be countersigning? must they be countersigning?
Perfect
must I have countersigned? must you have countersigned? must he have countersigned? must we have countersigned? must you have countersigned? must they have countersigned?
V-ing perfect
must I have been countersigning? must you have been countersigning? must he have been countersigning? must we have been countersigning? must you have been countersigning? must they have been countersigning?
Interro-negative form
Simple form
mustn't I countersign? mustn't you countersign? mustn't he countersign? mustn't we countersign? mustn't you countersign? mustn't they countersign?
V-ing form
mustn't I be countersigning? mustn't you be countersigning? mustn't he be countersigning? mustn't we be countersigning? mustn't you be countersigning? mustn't they be countersigning?
Perfect
mustn't I have countersigned? mustn't you have countersigned? mustn't he have countersigned? mustn't we have countersigned? mustn't you have countersigned? mustn't they have countersigned?
V-ing perfect
mustn't I have been countersigning? mustn't you have been countersigning? mustn't he have been countersigning? mustn't we have been countersigning? mustn't you have been countersigning? mustn't they have been countersigning?