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