I can backdate you can backdate she can backdate we can backdate you can backdate they can backdate
V-ing form
I can be backdating you can be backdating she can be backdating we can be backdating you can be backdating they can be backdating
Perfect
I can have backdated you can have backdated she can have backdated we can have backdated you can have backdated they can have backdated
V-ing perfect
I can have been backdating you can have been backdating she can have been backdating we can have been backdating you can have been backdating they can have been backdating
Negation
Simple form
I cannot backdate you cannot backdate she cannot backdate we cannot backdate you cannot backdate they cannot backdate
V-ing form
I cannot be backdating you cannot be backdating she cannot be backdating we cannot be backdating you cannot be backdating they cannot be backdating
Perfect
I cannot have backdated you cannot have backdated she cannot have backdated we cannot have backdated you cannot have backdated they cannot have backdated
V-ing perfect
I cannot have been backdating you cannot have been backdating she cannot have been backdating we cannot have been backdating you cannot have been backdating they cannot have been backdating
Interrogative form
Simple form
can I backdate? can you backdate? can she backdate? can we backdate? can you backdate? can they backdate?
V-ing form
can I be backdating? can you be backdating? can she be backdating? can we be backdating? can you be backdating? can they be backdating?
Perfect
can I have backdated? can you have backdated? can she have backdated? can we have backdated? can you have backdated? can they have backdated?
V-ing perfect
can I have been backdating? can you have been backdating? can she have been backdating? can we have been backdating? can you have been backdating? can they have been backdating?
Interro-negative form
Simple form
can I not backdate? can you not backdate? can she not backdate? can we not backdate? can you not backdate? can they not backdate?
V-ing form
can I not be backdating? can you not be backdating? can she not be backdating? can we not be backdating? can you not be backdating? can they not be backdating?
Perfect
can I not have backdated? can you not have backdated? can she not have backdated? can we not have backdated? can you not have backdated? can they not have backdated?
V-ing perfect
can I not have been backdating? can you not have been backdating? can she not have been backdating? can we not have been backdating? can you not have been backdating? can they not have been backdating?