Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I could warn warn you could warn warn he could warn warn we could warn warn you could warn warn they could warn warn
V-ing form
I could be warn warning you could be warn warning he could be warn warning we could be warn warning you could be warn warning they could be warn warning
Perfect
I could have warn warned you could have warn warned he could have warn warned we could have warn warned you could have warn warned they could have warn warned
V-ing perfect
I could have been warn warning you could have been warn warning he could have been warn warning we could have been warn warning you could have been warn warning they could have been warn warning
Negation
Simple form
I couldn't warn warn you couldn't warn warn he couldn't warn warn we couldn't warn warn you couldn't warn warn they couldn't warn warn
V-ing form
I couldn't be warn warning you couldn't be warn warning he couldn't be warn warning we couldn't be warn warning you couldn't be warn warning they couldn't be warn warning
Perfect
I couldn't have warn warned you couldn't have warn warned he couldn't have warn warned we couldn't have warn warned you couldn't have warn warned they couldn't have warn warned
V-ing perfect
I couldn't have been warn warning you couldn't have been warn warning he couldn't have been warn warning we couldn't have been warn warning you couldn't have been warn warning they couldn't have been warn warning
Interrogative form
Simple form
could I warn warn? could you warn warn? could he warn warn? could we warn warn? could you warn warn? could they warn warn?
V-ing form
could I be warn warning? could you be warn warning? could he be warn warning? could we be warn warning? could you be warn warning? could they be warn warning?
Perfect
could I have warn warned? could you have warn warned? could he have warn warned? could we have warn warned? could you have warn warned? could they have warn warned?
V-ing perfect
could I have been warn warning? could you have been warn warning? could he have been warn warning? could we have been warn warning? could you have been warn warning? could they have been warn warning?
Interro-negative form
Simple form
couldn't I warn warn? couldn't you warn warn? couldn't he warn warn? couldn't we warn warn? couldn't you warn warn? couldn't they warn warn?
V-ing form
couldn't I be warn warning? couldn't you be warn warning? couldn't he be warn warning? couldn't we be warn warning? couldn't you be warn warning? couldn't they be warn warning?
Perfect
couldn't I have warn warned? couldn't you have warn warned? couldn't he have warn warned? couldn't we have warn warned? couldn't you have warn warned? couldn't they have warn warned?
V-ing perfect
couldn't I have been warn warning? couldn't you have been warn warning? couldn't he have been warn warning? couldn't we have been warn warning? couldn't you have been warn warning? couldn't they have been warn warning?