I can retain you can retain he can retain we can retain you can retain they can retain
V-ing form
I can be retaining you can be retaining he can be retaining we can be retaining you can be retaining they can be retaining
Perfect
I can have retained you can have retained he can have retained we can have retained you can have retained they can have retained
V-ing perfect
I can have been retaining you can have been retaining he can have been retaining we can have been retaining you can have been retaining they can have been retaining
Negation
Simple form
I cannot retain you cannot retain he cannot retain we cannot retain you cannot retain they cannot retain
V-ing form
I cannot be retaining you cannot be retaining he cannot be retaining we cannot be retaining you cannot be retaining they cannot be retaining
Perfect
I cannot have retained you cannot have retained he cannot have retained we cannot have retained you cannot have retained they cannot have retained
V-ing perfect
I cannot have been retaining you cannot have been retaining he cannot have been retaining we cannot have been retaining you cannot have been retaining they cannot have been retaining
Interrogative form
Simple form
can I retain? can you retain? can he retain? can we retain? can you retain? can they retain?
V-ing form
can I be retaining? can you be retaining? can he be retaining? can we be retaining? can you be retaining? can they be retaining?
Perfect
can I have retained? can you have retained? can he have retained? can we have retained? can you have retained? can they have retained?
V-ing perfect
can I have been retaining? can you have been retaining? can he have been retaining? can we have been retaining? can you have been retaining? can they have been retaining?
Interro-negative form
Simple form
can I not retain? can you not retain? can he not retain? can we not retain? can you not retain? can they not retain?
V-ing form
can I not be retaining? can you not be retaining? can he not be retaining? can we not be retaining? can you not be retaining? can they not be retaining?
Perfect
can I not have retained? can you not have retained? can he not have retained? can we not have retained? can you not have retained? can they not have retained?
V-ing perfect
can I not have been retaining? can you not have been retaining? can he not have been retaining? can we not have been retaining? can you not have been retaining? can they not have been retaining?