I can frog you can frog he can frog we can frog you can frog they can frog
V-ing form
I can be froging you can be froging he can be froging we can be froging you can be froging they can be froging
Perfect
I can have froged you can have froged he can have froged we can have froged you can have froged they can have froged
V-ing perfect
I can have been froging you can have been froging he can have been froging we can have been froging you can have been froging they can have been froging
Negation
Simple form
I cannot frog you cannot frog he cannot frog we cannot frog you cannot frog they cannot frog
V-ing form
I cannot be froging you cannot be froging he cannot be froging we cannot be froging you cannot be froging they cannot be froging
Perfect
I cannot have froged you cannot have froged he cannot have froged we cannot have froged you cannot have froged they cannot have froged
V-ing perfect
I cannot have been froging you cannot have been froging he cannot have been froging we cannot have been froging you cannot have been froging they cannot have been froging
Interrogative form
Simple form
can I frog? can you frog? can he frog? can we frog? can you frog? can they frog?
V-ing form
can I be froging? can you be froging? can he be froging? can we be froging? can you be froging? can they be froging?
Perfect
can I have froged? can you have froged? can he have froged? can we have froged? can you have froged? can they have froged?
V-ing perfect
can I have been froging? can you have been froging? can he have been froging? can we have been froging? can you have been froging? can they have been froging?
Interro-negative form
Simple form
can I not frog? can you not frog? can he not frog? can we not frog? can you not frog? can they not frog?
V-ing form
can I not be froging? can you not be froging? can he not be froging? can we not be froging? can you not be froging? can they not be froging?
Perfect
can I not have froged? can you not have froged? can he not have froged? can we not have froged? can you not have froged? can they not have froged?
V-ing perfect
can I not have been froging? can you not have been froging? can he not have been froging? can we not have been froging? can you not have been froging? can they not have been froging?