I could breathe you could breathe he could breathe we could breathe you could breathe they could breathe
V-ing form
I could be breathing you could be breathing he could be breathing we could be breathing you could be breathing they could be breathing
Perfect
I could have breathed you could have breathed he could have breathed we could have breathed you could have breathed they could have breathed
V-ing perfect
I could have been breathing you could have been breathing he could have been breathing we could have been breathing you could have been breathing they could have been breathing
Negation
Simple form
I could not breathe you could not breathe he could not breathe we could not breathe you could not breathe they could not breathe
V-ing form
I could not be breathing you could not be breathing he could not be breathing we could not be breathing you could not be breathing they could not be breathing
Perfect
I could not have breathed you could not have breathed he could not have breathed we could not have breathed you could not have breathed they could not have breathed
V-ing perfect
I could not have been breathing you could not have been breathing he could not have been breathing we could not have been breathing you could not have been breathing they could not have been breathing
Interrogative form
Simple form
could I breathe? could you breathe? could he breathe? could we breathe? could you breathe? could they breathe?
V-ing form
could I be breathing? could you be breathing? could he be breathing? could we be breathing? could you be breathing? could they be breathing?
Perfect
could I have breathed? could you have breathed? could he have breathed? could we have breathed? could you have breathed? could they have breathed?
V-ing perfect
could I have been breathing? could you have been breathing? could he have been breathing? could we have been breathing? could you have been breathing? could they have been breathing?
Interro-negative form
Simple form
could I not breathe? could you not breathe? could he not breathe? could we not breathe? could you not breathe? could they not breathe?
V-ing form
could I not be breathing? could you not be breathing? could he not be breathing? could we not be breathing? could you not be breathing? could they not be breathing?
Perfect
could I not have breathed? could you not have breathed? could he not have breathed? could we not have breathed? could you not have breathed? could they not have breathed?
V-ing perfect
could I not have been breathing? could you not have been breathing? could he not have been breathing? could we not have been breathing? could you not have been breathing? could they not have been breathing?