I could leapfrog you could leapfrog he could leapfrog we could leapfrog you could leapfrog they could leapfrog
V-ing form
I could be leapfroging you could be leapfroging he could be leapfroging we could be leapfroging you could be leapfroging they could be leapfroging
Perfect
I could have leapfroged you could have leapfroged he could have leapfroged we could have leapfroged you could have leapfroged they could have leapfroged
V-ing perfect
I could have been leapfroging you could have been leapfroging he could have been leapfroging we could have been leapfroging you could have been leapfroging they could have been leapfroging
Negation
Simple form
I could not leapfrog you could not leapfrog he could not leapfrog we could not leapfrog you could not leapfrog they could not leapfrog
V-ing form
I could not be leapfroging you could not be leapfroging he could not be leapfroging we could not be leapfroging you could not be leapfroging they could not be leapfroging
Perfect
I could not have leapfroged you could not have leapfroged he could not have leapfroged we could not have leapfroged you could not have leapfroged they could not have leapfroged
V-ing perfect
I could not have been leapfroging you could not have been leapfroging he could not have been leapfroging we could not have been leapfroging you could not have been leapfroging they could not have been leapfroging
Interrogative form
Simple form
could I leapfrog? could you leapfrog? could he leapfrog? could we leapfrog? could you leapfrog? could they leapfrog?
V-ing form
could I be leapfroging? could you be leapfroging? could he be leapfroging? could we be leapfroging? could you be leapfroging? could they be leapfroging?
Perfect
could I have leapfroged? could you have leapfroged? could he have leapfroged? could we have leapfroged? could you have leapfroged? could they have leapfroged?
V-ing perfect
could I have been leapfroging? could you have been leapfroging? could he have been leapfroging? could we have been leapfroging? could you have been leapfroging? could they have been leapfroging?
Interro-negative form
Simple form
could I not leapfrog? could you not leapfrog? could he not leapfrog? could we not leapfrog? could you not leapfrog? could they not leapfrog?
V-ing form
could I not be leapfroging? could you not be leapfroging? could he not be leapfroging? could we not be leapfroging? could you not be leapfroging? could they not be leapfroging?
Perfect
could I not have leapfroged? could you not have leapfroged? could he not have leapfroged? could we not have leapfroged? could you not have leapfroged? could they not have leapfroged?
V-ing perfect
could I not have been leapfroging? could you not have been leapfroging? could he not have been leapfroging? could we not have been leapfroging? could you not have been leapfroging? could they not have been leapfroging?