I could retreat you could retreat he could retreat we could retreat you could retreat they could retreat
V-ing form
I could be retreating you could be retreating he could be retreating we could be retreating you could be retreating they could be retreating
Perfect
I could have retreated you could have retreated he could have retreated we could have retreated you could have retreated they could have retreated
V-ing perfect
I could have been retreating you could have been retreating he could have been retreating we could have been retreating you could have been retreating they could have been retreating
Negation
Simple form
I could not retreat you could not retreat he could not retreat we could not retreat you could not retreat they could not retreat
V-ing form
I could not be retreating you could not be retreating he could not be retreating we could not be retreating you could not be retreating they could not be retreating
Perfect
I could not have retreated you could not have retreated he could not have retreated we could not have retreated you could not have retreated they could not have retreated
V-ing perfect
I could not have been retreating you could not have been retreating he could not have been retreating we could not have been retreating you could not have been retreating they could not have been retreating
Interrogative form
Simple form
could I retreat? could you retreat? could he retreat? could we retreat? could you retreat? could they retreat?
V-ing form
could I be retreating? could you be retreating? could he be retreating? could we be retreating? could you be retreating? could they be retreating?
Perfect
could I have retreated? could you have retreated? could he have retreated? could we have retreated? could you have retreated? could they have retreated?
V-ing perfect
could I have been retreating? could you have been retreating? could he have been retreating? could we have been retreating? could you have been retreating? could they have been retreating?
Interro-negative form
Simple form
could I not retreat? could you not retreat? could he not retreat? could we not retreat? could you not retreat? could they not retreat?
V-ing form
could I not be retreating? could you not be retreating? could he not be retreating? could we not be retreating? could you not be retreating? could they not be retreating?
Perfect
could I not have retreated? could you not have retreated? could he not have retreated? could we not have retreated? could you not have retreated? could they not have retreated?
V-ing perfect
could I not have been retreating? could you not have been retreating? could he not have been retreating? could we not have been retreating? could you not have been retreating? could they not have been retreating?