Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I could stain sth you could stain sth she could stain sth we could stain sth you could stain sth they could stain sth
V-ing form
I could be stain sthing you could be stain sthing she could be stain sthing we could be stain sthing you could be stain sthing they could be stain sthing
Perfect
I could have stain sthed you could have stain sthed she could have stain sthed we could have stain sthed you could have stain sthed they could have stain sthed
V-ing perfect
I could have been stain sthing you could have been stain sthing she could have been stain sthing we could have been stain sthing you could have been stain sthing they could have been stain sthing
Negation
Simple form
I could not stain sth you could not stain sth she could not stain sth we could not stain sth you could not stain sth they could not stain sth
V-ing form
I could not be stain sthing you could not be stain sthing she could not be stain sthing we could not be stain sthing you could not be stain sthing they could not be stain sthing
Perfect
I could not have stain sthed you could not have stain sthed she could not have stain sthed we could not have stain sthed you could not have stain sthed they could not have stain sthed
V-ing perfect
I could not have been stain sthing you could not have been stain sthing she could not have been stain sthing we could not have been stain sthing you could not have been stain sthing they could not have been stain sthing
Interrogative form
Simple form
could I stain sth? could you stain sth? could she stain sth? could we stain sth? could you stain sth? could they stain sth?
V-ing form
could I be stain sthing? could you be stain sthing? could she be stain sthing? could we be stain sthing? could you be stain sthing? could they be stain sthing?
Perfect
could I have stain sthed? could you have stain sthed? could she have stain sthed? could we have stain sthed? could you have stain sthed? could they have stain sthed?
V-ing perfect
could I have been stain sthing? could you have been stain sthing? could she have been stain sthing? could we have been stain sthing? could you have been stain sthing? could they have been stain sthing?
Interro-negative form
Simple form
could I not stain sth? could you not stain sth? could she not stain sth? could we not stain sth? could you not stain sth? could they not stain sth?
V-ing form
could I not be stain sthing? could you not be stain sthing? could she not be stain sthing? could we not be stain sthing? could you not be stain sthing? could they not be stain sthing?
Perfect
could I not have stain sthed? could you not have stain sthed? could she not have stain sthed? could we not have stain sthed? could you not have stain sthed? could they not have stain sthed?
V-ing perfect
could I not have been stain sthing? could you not have been stain sthing? could she not have been stain sthing? could we not have been stain sthing? could you not have been stain sthing? could they not have been stain sthing?