I could butterfly you could butterfly he could butterfly we could butterfly you could butterfly they could butterfly
V-ing form
I could be butterflying you could be butterflying he could be butterflying we could be butterflying you could be butterflying they could be butterflying
Perfect
I could have butterflied you could have butterflied he could have butterflied we could have butterflied you could have butterflied they could have butterflied
V-ing perfect
I could have been butterflying you could have been butterflying he could have been butterflying we could have been butterflying you could have been butterflying they could have been butterflying
Negation
Simple form
I could not butterfly you could not butterfly he could not butterfly we could not butterfly you could not butterfly they could not butterfly
V-ing form
I could not be butterflying you could not be butterflying he could not be butterflying we could not be butterflying you could not be butterflying they could not be butterflying
Perfect
I could not have butterflied you could not have butterflied he could not have butterflied we could not have butterflied you could not have butterflied they could not have butterflied
V-ing perfect
I could not have been butterflying you could not have been butterflying he could not have been butterflying we could not have been butterflying you could not have been butterflying they could not have been butterflying
Interrogative form
Simple form
could I butterfly? could you butterfly? could he butterfly? could we butterfly? could you butterfly? could they butterfly?
V-ing form
could I be butterflying? could you be butterflying? could he be butterflying? could we be butterflying? could you be butterflying? could they be butterflying?
Perfect
could I have butterflied? could you have butterflied? could he have butterflied? could we have butterflied? could you have butterflied? could they have butterflied?
V-ing perfect
could I have been butterflying? could you have been butterflying? could he have been butterflying? could we have been butterflying? could you have been butterflying? could they have been butterflying?
Interro-negative form
Simple form
could I not butterfly? could you not butterfly? could he not butterfly? could we not butterfly? could you not butterfly? could they not butterfly?
V-ing form
could I not be butterflying? could you not be butterflying? could he not be butterflying? could we not be butterflying? could you not be butterflying? could they not be butterflying?
Perfect
could I not have butterflied? could you not have butterflied? could he not have butterflied? could we not have butterflied? could you not have butterflied? could they not have butterflied?
V-ing perfect
could I not have been butterflying? could you not have been butterflying? could he not have been butterflying? could we not have been butterflying? could you not have been butterflying? could they not have been butterflying?