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 can't countersign you can't countersign she can't countersign we can't countersign you can't countersign they can't countersign
V-ing form
I can't be countersigning you can't be countersigning she can't be countersigning we can't be countersigning you can't be countersigning they can't be countersigning
Perfect
I can't have countersigned you can't have countersigned she can't have countersigned we can't have countersigned you can't have countersigned they can't have countersigned
V-ing perfect
I can't have been countersigning you can't have been countersigning she can't have been countersigning we can't have been countersigning you can't have been countersigning they can't 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't I countersign? can't you countersign? can't she countersign? can't we countersign? can't you countersign? can't they countersign?
V-ing form
can't I be countersigning? can't you be countersigning? can't she be countersigning? can't we be countersigning? can't you be countersigning? can't they be countersigning?
Perfect
can't I have countersigned? can't you have countersigned? can't she have countersigned? can't we have countersigned? can't you have countersigned? can't they have countersigned?
V-ing perfect
can't I have been countersigning? can't you have been countersigning? can't she have been countersigning? can't we have been countersigning? can't you have been countersigning? can't they have been countersigning?