I could fringe you could fringe he could fringe we could fringe you could fringe they could fringe
V-ing form
I could be fringing you could be fringing he could be fringing we could be fringing you could be fringing they could be fringing
Perfect
I could have fringed you could have fringed he could have fringed we could have fringed you could have fringed they could have fringed
V-ing perfect
I could have been fringing you could have been fringing he could have been fringing we could have been fringing you could have been fringing they could have been fringing
Negation
Simple form
I could not fringe you could not fringe he could not fringe we could not fringe you could not fringe they could not fringe
V-ing form
I could not be fringing you could not be fringing he could not be fringing we could not be fringing you could not be fringing they could not be fringing
Perfect
I could not have fringed you could not have fringed he could not have fringed we could not have fringed you could not have fringed they could not have fringed
V-ing perfect
I could not have been fringing you could not have been fringing he could not have been fringing we could not have been fringing you could not have been fringing they could not have been fringing
Interrogative form
Simple form
could I fringe? could you fringe? could he fringe? could we fringe? could you fringe? could they fringe?
V-ing form
could I be fringing? could you be fringing? could he be fringing? could we be fringing? could you be fringing? could they be fringing?
Perfect
could I have fringed? could you have fringed? could he have fringed? could we have fringed? could you have fringed? could they have fringed?
V-ing perfect
could I have been fringing? could you have been fringing? could he have been fringing? could we have been fringing? could you have been fringing? could they have been fringing?
Interro-negative form
Simple form
could I not fringe? could you not fringe? could he not fringe? could we not fringe? could you not fringe? could they not fringe?
V-ing form
could I not be fringing? could you not be fringing? could he not be fringing? could we not be fringing? could you not be fringing? could they not be fringing?
Perfect
could I not have fringed? could you not have fringed? could he not have fringed? could we not have fringed? could you not have fringed? could they not have fringed?
V-ing perfect
could I not have been fringing? could you not have been fringing? could he not have been fringing? could we not have been fringing? could you not have been fringing? could they not have been fringing?