I could release you could release he could release we could release you could release they could release
V-ing form
I could be releasing you could be releasing he could be releasing we could be releasing you could be releasing they could be releasing
Perfect
I could have released you could have released he could have released we could have released you could have released they could have released
V-ing perfect
I could have been releasing you could have been releasing he could have been releasing we could have been releasing you could have been releasing they could have been releasing
Negation
Simple form
I couldn't release you couldn't release he couldn't release we couldn't release you couldn't release they couldn't release
V-ing form
I couldn't be releasing you couldn't be releasing he couldn't be releasing we couldn't be releasing you couldn't be releasing they couldn't be releasing
Perfect
I couldn't have released you couldn't have released he couldn't have released we couldn't have released you couldn't have released they couldn't have released
V-ing perfect
I couldn't have been releasing you couldn't have been releasing he couldn't have been releasing we couldn't have been releasing you couldn't have been releasing they couldn't have been releasing
Interrogative form
Simple form
could I release? could you release? could he release? could we release? could you release? could they release?
V-ing form
could I be releasing? could you be releasing? could he be releasing? could we be releasing? could you be releasing? could they be releasing?
Perfect
could I have released? could you have released? could he have released? could we have released? could you have released? could they have released?
V-ing perfect
could I have been releasing? could you have been releasing? could he have been releasing? could we have been releasing? could you have been releasing? could they have been releasing?
Interro-negative form
Simple form
couldn't I release? couldn't you release? couldn't he release? couldn't we release? couldn't you release? couldn't they release?
V-ing form
couldn't I be releasing? couldn't you be releasing? couldn't he be releasing? couldn't we be releasing? couldn't you be releasing? couldn't they be releasing?
Perfect
couldn't I have released? couldn't you have released? couldn't he have released? couldn't we have released? couldn't you have released? couldn't they have released?
V-ing perfect
couldn't I have been releasing? couldn't you have been releasing? couldn't he have been releasing? couldn't we have been releasing? couldn't you have been releasing? couldn't they have been releasing?