I could countersign you could countersign he could countersign we could countersign you could countersign they could countersign
V-ing form
I could be countersigning you could be countersigning he could be countersigning we could be countersigning you could be countersigning they could be countersigning
Perfect
I could have countersigned you could have countersigned he could have countersigned we could have countersigned you could have countersigned they could have countersigned
V-ing perfect
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
Negation
Simple form
I could not countersign you could not countersign he could not countersign we could not countersign you could not countersign they could not countersign
V-ing form
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
Perfect
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
V-ing perfect
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
Interrogative form
Simple form
could I countersign? could you countersign? could he countersign? could we countersign? could you countersign? could they countersign?
V-ing form
could I be countersigning? could you be countersigning? could he be countersigning? could we be countersigning? could you be countersigning? could they be countersigning?
Perfect
could I have countersigned? could you have countersigned? could he have countersigned? could we have countersigned? could you have countersigned? could they have countersigned?
V-ing perfect
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?
Interro-negative form
Simple form
could I not countersign? could you not countersign? could he not countersign? could we not countersign? could you not countersign? could they not countersign?
V-ing form
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?
Perfect
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?
V-ing perfect
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?