I can vary you can vary she can vary we can vary you can vary they can vary
V-ing form
I can be varying you can be varying she can be varying we can be varying you can be varying they can be varying
Perfect
I can have varied you can have varied she can have varied we can have varied you can have varied they can have varied
V-ing perfect
I can have been varying you can have been varying she can have been varying we can have been varying you can have been varying they can have been varying
Negation
Simple form
I cannot vary you cannot vary she cannot vary we cannot vary you cannot vary they cannot vary
V-ing form
I cannot be varying you cannot be varying she cannot be varying we cannot be varying you cannot be varying they cannot be varying
Perfect
I cannot have varied you cannot have varied she cannot have varied we cannot have varied you cannot have varied they cannot have varied
V-ing perfect
I cannot have been varying you cannot have been varying she cannot have been varying we cannot have been varying you cannot have been varying they cannot have been varying
Interrogative form
Simple form
can I vary? can you vary? can she vary? can we vary? can you vary? can they vary?
V-ing form
can I be varying? can you be varying? can she be varying? can we be varying? can you be varying? can they be varying?
Perfect
can I have varied? can you have varied? can she have varied? can we have varied? can you have varied? can they have varied?
V-ing perfect
can I have been varying? can you have been varying? can she have been varying? can we have been varying? can you have been varying? can they have been varying?
Interro-negative form
Simple form
can I not vary? can you not vary? can she not vary? can we not vary? can you not vary? can they not vary?
V-ing form
can I not be varying? can you not be varying? can she not be varying? can we not be varying? can you not be varying? can they not be varying?
Perfect
can I not have varied? can you not have varied? can she not have varied? can we not have varied? can you not have varied? can they not have varied?
V-ing perfect
can I not have been varying? can you not have been varying? can she not have been varying? can we not have been varying? can you not have been varying? can they not have been varying?