I could breathe you could breathe she could breathe we could breathe you could breathe they could breathe
V-ing form
I could be breathing you could be breathing she could be breathing we could be breathing you could be breathing they could be breathing
Perfect
I could have breathed you could have breathed she 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 she could have been breathing we could have been breathing you could have been breathing they could have been breathing
Negation
Simple form
I couldn't breathe you couldn't breathe she couldn't breathe we couldn't breathe you couldn't breathe they couldn't breathe
V-ing form
I couldn't be breathing you couldn't be breathing she couldn't be breathing we couldn't be breathing you couldn't be breathing they couldn't be breathing
Perfect
I couldn't have breathed you couldn't have breathed she couldn't have breathed we couldn't have breathed you couldn't have breathed they couldn't have breathed
V-ing perfect
I couldn't have been breathing you couldn't have been breathing she couldn't have been breathing we couldn't have been breathing you couldn't have been breathing they couldn't have been breathing
Interrogative form
Simple form
could I breathe? could you breathe? could she breathe? could we breathe? could you breathe? could they breathe?
V-ing form
could I be breathing? could you be breathing? could she be breathing? could we be breathing? could you be breathing? could they be breathing?
Perfect
could I have breathed? could you have breathed? could she 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 she have been breathing? could we have been breathing? could you have been breathing? could they have been breathing?
Interro-negative form
Simple form
couldn't I breathe? couldn't you breathe? couldn't she breathe? couldn't we breathe? couldn't you breathe? couldn't they breathe?
V-ing form
couldn't I be breathing? couldn't you be breathing? couldn't she be breathing? couldn't we be breathing? couldn't you be breathing? couldn't they be breathing?
Perfect
couldn't I have breathed? couldn't you have breathed? couldn't she have breathed? couldn't we have breathed? couldn't you have breathed? couldn't they have breathed?
V-ing perfect
couldn't I have been breathing? couldn't you have been breathing? couldn't she have been breathing? couldn't we have been breathing? couldn't you have been breathing? couldn't they have been breathing?