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