I can countersign you can countersign she can countersign we can countersign you can countersign they can countersign
V-ing form
I can be countersigning you can be countersigning she can be countersigning we can be countersigning you can be countersigning they can be countersigning
Perfect
I can have countersigned you can have countersigned she can have countersigned we can have countersigned you can have countersigned they can have countersigned
V-ing perfect
I can have been countersigning you can have been countersigning she can have been countersigning we can have been countersigning you can have been countersigning they can have been countersigning
Negation
Simple form
I cannot countersign you cannot countersign she cannot countersign we cannot countersign you cannot countersign they cannot countersign
V-ing form
I cannot be countersigning you cannot be countersigning she cannot be countersigning we cannot be countersigning you cannot be countersigning they cannot be countersigning
Perfect
I cannot have countersigned you cannot have countersigned she cannot have countersigned we cannot have countersigned you cannot have countersigned they cannot have countersigned
V-ing perfect
I cannot have been countersigning you cannot have been countersigning she cannot have been countersigning we cannot have been countersigning you cannot have been countersigning they cannot have been countersigning
Interrogative form
Simple form
can I countersign? can you countersign? can she countersign? can we countersign? can you countersign? can they countersign?
V-ing form
can I be countersigning? can you be countersigning? can she be countersigning? can we be countersigning? can you be countersigning? can they be countersigning?
Perfect
can I have countersigned? can you have countersigned? can she have countersigned? can we have countersigned? can you have countersigned? can they have countersigned?
V-ing perfect
can I have been countersigning? can you have been countersigning? can she have been countersigning? can we have been countersigning? can you have been countersigning? can they have been countersigning?
Interro-negative form
Simple form
can I not countersign? can you not countersign? can she not countersign? can we not countersign? can you not countersign? can they not countersign?
V-ing form
can I not be countersigning? can you not be countersigning? can she not be countersigning? can we not be countersigning? can you not be countersigning? can they not be countersigning?
Perfect
can I not have countersigned? can you not have countersigned? can she not have countersigned? can we not have countersigned? can you not have countersigned? can they not have countersigned?
V-ing perfect
can I not have been countersigning? can you not have been countersigning? can she not have been countersigning? can we not have been countersigning? can you not have been countersigning? can they not have been countersigning?