could countersign
Regular verb: countersign - countersigned- countersigned

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

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not countersign
you could not countersign
she 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
she 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
she 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
she could not have been countersigning
we could not have been countersigning
you could not have been countersigning
they could not have been countersigning	

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

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not countersign?
could you not countersign?
could she 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 she 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 she 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 she not have been countersigning?
could we not have been countersigning?
could you not have been countersigning?
could they not have been countersigning?