could countersign
Verbo regular: countersign - countersigned- countersigned

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

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

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

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