Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I could die down you could die down he could die down we could die down you could die down they could die down
V-ing form
I could be die downing you could be die downing he could be die downing we could be die downing you could be die downing they could be die downing
Perfect
I could have die downed you could have die downed he could have die downed we could have die downed you could have die downed they could have die downed
V-ing perfect
I could have been die downing you could have been die downing he could have been die downing we could have been die downing you could have been die downing they could have been die downing
Negation
Simple form
I could not die down you could not die down he could not die down we could not die down you could not die down they could not die down
V-ing form
I could not be die downing you could not be die downing he could not be die downing we could not be die downing you could not be die downing they could not be die downing
Perfect
I could not have die downed you could not have die downed he could not have die downed we could not have die downed you could not have die downed they could not have die downed
V-ing perfect
I could not have been die downing you could not have been die downing he could not have been die downing we could not have been die downing you could not have been die downing they could not have been die downing
Interrogative form
Simple form
could I die down? could you die down? could he die down? could we die down? could you die down? could they die down?
V-ing form
could I be die downing? could you be die downing? could he be die downing? could we be die downing? could you be die downing? could they be die downing?
Perfect
could I have die downed? could you have die downed? could he have die downed? could we have die downed? could you have die downed? could they have die downed?
V-ing perfect
could I have been die downing? could you have been die downing? could he have been die downing? could we have been die downing? could you have been die downing? could they have been die downing?
Interro-negative form
Simple form
could I not die down? could you not die down? could he not die down? could we not die down? could you not die down? could they not die down?
V-ing form
could I not be die downing? could you not be die downing? could he not be die downing? could we not be die downing? could you not be die downing? could they not be die downing?
Perfect
could I not have die downed? could you not have die downed? could he not have die downed? could we not have die downed? could you not have die downed? could they not have die downed?
V-ing perfect
could I not have been die downing? could you not have been die downing? could he not have been die downing? could we not have been die downing? could you not have been die downing? could they not have been die downing?