I could squeal you could squeal he could squeal we could squeal you could squeal they could squeal
V-ing form
I could be squealing you could be squealing he could be squealing we could be squealing you could be squealing they could be squealing
Perfect
I could have squealed you could have squealed he could have squealed we could have squealed you could have squealed they could have squealed
V-ing perfect
I could have been squealing you could have been squealing he could have been squealing we could have been squealing you could have been squealing they could have been squealing
Negation
Simple form
I couldn't squeal you couldn't squeal he couldn't squeal we couldn't squeal you couldn't squeal they couldn't squeal
V-ing form
I couldn't be squealing you couldn't be squealing he couldn't be squealing we couldn't be squealing you couldn't be squealing they couldn't be squealing
Perfect
I couldn't have squealed you couldn't have squealed he couldn't have squealed we couldn't have squealed you couldn't have squealed they couldn't have squealed
V-ing perfect
I couldn't have been squealing you couldn't have been squealing he couldn't have been squealing we couldn't have been squealing you couldn't have been squealing they couldn't have been squealing
Interrogative form
Simple form
could I squeal? could you squeal? could he squeal? could we squeal? could you squeal? could they squeal?
V-ing form
could I be squealing? could you be squealing? could he be squealing? could we be squealing? could you be squealing? could they be squealing?
Perfect
could I have squealed? could you have squealed? could he have squealed? could we have squealed? could you have squealed? could they have squealed?
V-ing perfect
could I have been squealing? could you have been squealing? could he have been squealing? could we have been squealing? could you have been squealing? could they have been squealing?
Interro-negative form
Simple form
couldn't I squeal? couldn't you squeal? couldn't he squeal? couldn't we squeal? couldn't you squeal? couldn't they squeal?
V-ing form
couldn't I be squealing? couldn't you be squealing? couldn't he be squealing? couldn't we be squealing? couldn't you be squealing? couldn't they be squealing?
Perfect
couldn't I have squealed? couldn't you have squealed? couldn't he have squealed? couldn't we have squealed? couldn't you have squealed? couldn't they have squealed?
V-ing perfect
couldn't I have been squealing? couldn't you have been squealing? couldn't he have been squealing? couldn't we have been squealing? couldn't you have been squealing? couldn't they have been squealing?