I can retighten you can retighten he can retighten we can retighten you can retighten they can retighten
V-ing form
I can be retightening you can be retightening he can be retightening we can be retightening you can be retightening they can be retightening
Perfect
I can have retightened you can have retightened he can have retightened we can have retightened you can have retightened they can have retightened
V-ing perfect
I can have been retightening you can have been retightening he can have been retightening we can have been retightening you can have been retightening they can have been retightening
Negation
Simple form
I cannot retighten you cannot retighten he cannot retighten we cannot retighten you cannot retighten they cannot retighten
V-ing form
I cannot be retightening you cannot be retightening he cannot be retightening we cannot be retightening you cannot be retightening they cannot be retightening
Perfect
I cannot have retightened you cannot have retightened he cannot have retightened we cannot have retightened you cannot have retightened they cannot have retightened
V-ing perfect
I cannot have been retightening you cannot have been retightening he cannot have been retightening we cannot have been retightening you cannot have been retightening they cannot have been retightening
Interrogative form
Simple form
can I retighten? can you retighten? can he retighten? can we retighten? can you retighten? can they retighten?
V-ing form
can I be retightening? can you be retightening? can he be retightening? can we be retightening? can you be retightening? can they be retightening?
Perfect
can I have retightened? can you have retightened? can he have retightened? can we have retightened? can you have retightened? can they have retightened?
V-ing perfect
can I have been retightening? can you have been retightening? can he have been retightening? can we have been retightening? can you have been retightening? can they have been retightening?
Interro-negative form
Simple form
can I not retighten? can you not retighten? can he not retighten? can we not retighten? can you not retighten? can they not retighten?
V-ing form
can I not be retightening? can you not be retightening? can he not be retightening? can we not be retightening? can you not be retightening? can they not be retightening?
Perfect
can I not have retightened? can you not have retightened? can he not have retightened? can we not have retightened? can you not have retightened? can they not have retightened?
V-ing perfect
can I not have been retightening? can you not have been retightening? can he not have been retightening? can we not have been retightening? can you not have been retightening? can they not have been retightening?