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