I can retard you can retard she can retard we can retard you can retard they can retard
V-ing form
I can be retarding you can be retarding she can be retarding we can be retarding you can be retarding they can be retarding
Perfect
I can have retarded you can have retarded she can have retarded we can have retarded you can have retarded they can have retarded
V-ing perfect
I can have been retarding you can have been retarding she can have been retarding we can have been retarding you can have been retarding they can have been retarding
Negation
Simple form
I cannot retard you cannot retard she cannot retard we cannot retard you cannot retard they cannot retard
V-ing form
I cannot be retarding you cannot be retarding she cannot be retarding we cannot be retarding you cannot be retarding they cannot be retarding
Perfect
I cannot have retarded you cannot have retarded she cannot have retarded we cannot have retarded you cannot have retarded they cannot have retarded
V-ing perfect
I cannot have been retarding you cannot have been retarding she cannot have been retarding we cannot have been retarding you cannot have been retarding they cannot have been retarding
Interrogative form
Simple form
can I retard? can you retard? can she retard? can we retard? can you retard? can they retard?
V-ing form
can I be retarding? can you be retarding? can she be retarding? can we be retarding? can you be retarding? can they be retarding?
Perfect
can I have retarded? can you have retarded? can she have retarded? can we have retarded? can you have retarded? can they have retarded?
V-ing perfect
can I have been retarding? can you have been retarding? can she have been retarding? can we have been retarding? can you have been retarding? can they have been retarding?
Interro-negative form
Simple form
can I not retard? can you not retard? can she not retard? can we not retard? can you not retard? can they not retard?
V-ing form
can I not be retarding? can you not be retarding? can she not be retarding? can we not be retarding? can you not be retarding? can they not be retarding?
Perfect
can I not have retarded? can you not have retarded? can she not have retarded? can we not have retarded? can you not have retarded? can they not have retarded?
V-ing perfect
can I not have been retarding? can you not have been retarding? can she not have been retarding? can we not have been retarding? can you not have been retarding? can they not have been retarding?