must countersign
Verbo regular: countersign - countersigned- countersigned

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must countersign
you must countersign
he must countersign
we must countersign
you must countersign
they must countersign 	I must be countersigning
you must be countersigning
he must be countersigning
we must be countersigning
you must be countersigning
they must be countersigning	I must have countersigned
you must have countersigned
he 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
he must have been countersigning
we must have been countersigning
you must have been countersigning
they must have been countersigning	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must not countersign
you must not countersign
he must not countersign
we must not countersign
you must not countersign
they must not countersign 	I must not be countersigning
you must not be countersigning
he must not be countersigning
we must not be countersigning
you must not be countersigning
they must not be countersigning	I must not have countersigned
you must not have countersigned
he must not have countersigned
we must not have countersigned
you must not have countersigned
they must not have countersigned	I must not have been countersigning
you must not have been countersigning
he must not have been countersigning
we must not have been countersigning
you must not have been countersigning
they must not have been countersigning	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I countersign?
must you countersign?
must he countersign?
must we countersign?
must you countersign?
must they countersign? 	must I be countersigning?
must you be countersigning?
must he be countersigning?
must we be countersigning?
must you be countersigning?
must they be countersigning? 	must I have countersigned?
must you have countersigned?
must he 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 he have been countersigning?
must we have been countersigning?
must you have been countersigning?
must they have been countersigning? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I not countersign?
must you not countersign?
must he not countersign?
must we not countersign?
must you not countersign?
must they not countersign? 	must I not be countersigning?
must you not be countersigning?
must he not be countersigning?
must we not be countersigning?
must you not be countersigning?
must they not be countersigning? 	must I not have countersigned?
must you not have countersigned?
must he not have countersigned?
must we not have countersigned?
must you not have countersigned?
must they not have countersigned? 	must I not have been countersigning?
must you not have been countersigning?
must he not have been countersigning?
must we not have been countersigning?
must you not have been countersigning?
must they not have been countersigning?