I could destain you could destain he could destain we could destain you could destain they could destain
V-ing form
I could be destaining you could be destaining he could be destaining we could be destaining you could be destaining they could be destaining
Perfect
I could have destained you could have destained he could have destained we could have destained you could have destained they could have destained
V-ing perfect
I could have been destaining you could have been destaining he could have been destaining we could have been destaining you could have been destaining they could have been destaining
Negation
Simple form
I could not destain you could not destain he could not destain we could not destain you could not destain they could not destain
V-ing form
I could not be destaining you could not be destaining he could not be destaining we could not be destaining you could not be destaining they could not be destaining
Perfect
I could not have destained you could not have destained he could not have destained we could not have destained you could not have destained they could not have destained
V-ing perfect
I could not have been destaining you could not have been destaining he could not have been destaining we could not have been destaining you could not have been destaining they could not have been destaining
Interrogative form
Simple form
could I destain? could you destain? could he destain? could we destain? could you destain? could they destain?
V-ing form
could I be destaining? could you be destaining? could he be destaining? could we be destaining? could you be destaining? could they be destaining?
Perfect
could I have destained? could you have destained? could he have destained? could we have destained? could you have destained? could they have destained?
V-ing perfect
could I have been destaining? could you have been destaining? could he have been destaining? could we have been destaining? could you have been destaining? could they have been destaining?
Interro-negative form
Simple form
could I not destain? could you not destain? could he not destain? could we not destain? could you not destain? could they not destain?
V-ing form
could I not be destaining? could you not be destaining? could he not be destaining? could we not be destaining? could you not be destaining? could they not be destaining?
Perfect
could I not have destained? could you not have destained? could he not have destained? could we not have destained? could you not have destained? could they not have destained?
V-ing perfect
could I not have been destaining? could you not have been destaining? could he not have been destaining? could we not have been destaining? could you not have been destaining? could they not have been destaining?