I can forget you can forget he can forget we can forget you can forget they can forget
V-ing form
I can be forgetting you can be forgetting he can be forgetting we can be forgetting you can be forgetting they can be forgetting
Perfect
I can have forgotten you can have forgotten he can have forgotten we can have forgotten you can have forgotten they can have forgotten
V-ing perfect
I can have been forgetting you can have been forgetting he can have been forgetting we can have been forgetting you can have been forgetting they can have been forgetting
Negation
Simple form
I can't forget you can't forget he can't forget we can't forget you can't forget they can't forget
V-ing form
I can't be forgetting you can't be forgetting he can't be forgetting we can't be forgetting you can't be forgetting they can't be forgetting
Perfect
I can't have forgotten you can't have forgotten he can't have forgotten we can't have forgotten you can't have forgotten they can't have forgotten
V-ing perfect
I can't have been forgetting you can't have been forgetting he can't have been forgetting we can't have been forgetting you can't have been forgetting they can't have been forgetting
Interrogative form
Simple form
can I forget? can you forget? can he forget? can we forget? can you forget? can they forget?
V-ing form
can I be forgetting? can you be forgetting? can he be forgetting? can we be forgetting? can you be forgetting? can they be forgetting?
Perfect
can I have forgotten? can you have forgotten? can he have forgotten? can we have forgotten? can you have forgotten? can they have forgotten?
V-ing perfect
can I have been forgetting? can you have been forgetting? can he have been forgetting? can we have been forgetting? can you have been forgetting? can they have been forgetting?
Interro-negative form
Simple form
can't I forget? can't you forget? can't he forget? can't we forget? can't you forget? can't they forget?
V-ing form
can't I be forgetting? can't you be forgetting? can't he be forgetting? can't we be forgetting? can't you be forgetting? can't they be forgetting?
Perfect
can't I have forgotten? can't you have forgotten? can't he have forgotten? can't we have forgotten? can't you have forgotten? can't they have forgotten?
V-ing perfect
can't I have been forgetting? can't you have been forgetting? can't he have been forgetting? can't we have been forgetting? can't you have been forgetting? can't they have been forgetting?