I could melt you could melt he could melt we could melt you could melt they could melt
V-ing form
I could be melting you could be melting he could be melting we could be melting you could be melting they could be melting
Perfect
I could have melted you could have melted he could have melted we could have melted you could have melted they could have melted
V-ing perfect
I could have been melting you could have been melting he could have been melting we could have been melting you could have been melting they could have been melting
Negation
Simple form
I could not melt you could not melt he could not melt we could not melt you could not melt they could not melt
V-ing form
I could not be melting you could not be melting he could not be melting we could not be melting you could not be melting they could not be melting
Perfect
I could not have melted you could not have melted he could not have melted we could not have melted you could not have melted they could not have melted
V-ing perfect
I could not have been melting you could not have been melting he could not have been melting we could not have been melting you could not have been melting they could not have been melting
Interrogative form
Simple form
could I melt? could you melt? could he melt? could we melt? could you melt? could they melt?
V-ing form
could I be melting? could you be melting? could he be melting? could we be melting? could you be melting? could they be melting?
Perfect
could I have melted? could you have melted? could he have melted? could we have melted? could you have melted? could they have melted?
V-ing perfect
could I have been melting? could you have been melting? could he have been melting? could we have been melting? could you have been melting? could they have been melting?
Interro-negative form
Simple form
could I not melt? could you not melt? could he not melt? could we not melt? could you not melt? could they not melt?
V-ing form
could I not be melting? could you not be melting? could he not be melting? could we not be melting? could you not be melting? could they not be melting?
Perfect
could I not have melted? could you not have melted? could he not have melted? could we not have melted? could you not have melted? could they not have melted?
V-ing perfect
could I not have been melting? could you not have been melting? could he not have been melting? could we not have been melting? could you not have been melting? could they not have been melting?