I could summersault you could summersault he could summersault we could summersault you could summersault they could summersault
V-ing form
I could be summersaulting you could be summersaulting he could be summersaulting we could be summersaulting you could be summersaulting they could be summersaulting
Perfect
I could have summersaulted you could have summersaulted he could have summersaulted we could have summersaulted you could have summersaulted they could have summersaulted
V-ing perfect
I could have been summersaulting you could have been summersaulting he could have been summersaulting we could have been summersaulting you could have been summersaulting they could have been summersaulting
Negation
Simple form
I could not summersault you could not summersault he could not summersault we could not summersault you could not summersault they could not summersault
V-ing form
I could not be summersaulting you could not be summersaulting he could not be summersaulting we could not be summersaulting you could not be summersaulting they could not be summersaulting
Perfect
I could not have summersaulted you could not have summersaulted he could not have summersaulted we could not have summersaulted you could not have summersaulted they could not have summersaulted
V-ing perfect
I could not have been summersaulting you could not have been summersaulting he could not have been summersaulting we could not have been summersaulting you could not have been summersaulting they could not have been summersaulting
Interrogative form
Simple form
could I summersault? could you summersault? could he summersault? could we summersault? could you summersault? could they summersault?
V-ing form
could I be summersaulting? could you be summersaulting? could he be summersaulting? could we be summersaulting? could you be summersaulting? could they be summersaulting?
Perfect
could I have summersaulted? could you have summersaulted? could he have summersaulted? could we have summersaulted? could you have summersaulted? could they have summersaulted?
V-ing perfect
could I have been summersaulting? could you have been summersaulting? could he have been summersaulting? could we have been summersaulting? could you have been summersaulting? could they have been summersaulting?
Interro-negative form
Simple form
could I not summersault? could you not summersault? could he not summersault? could we not summersault? could you not summersault? could they not summersault?
V-ing form
could I not be summersaulting? could you not be summersaulting? could he not be summersaulting? could we not be summersaulting? could you not be summersaulting? could they not be summersaulting?
Perfect
could I not have summersaulted? could you not have summersaulted? could he not have summersaulted? could we not have summersaulted? could you not have summersaulted? could they not have summersaulted?
V-ing perfect
could I not have been summersaulting? could you not have been summersaulting? could he not have been summersaulting? could we not have been summersaulting? could you not have been summersaulting? could they not have been summersaulting?