could overturn
Regular verb: overturn - overturned- overturned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could overturn
you could overturn
he could overturn
we could overturn
you could overturn
they could overturn 	I could be overturning
you could be overturning
he could be overturning
we could be overturning
you could be overturning
they could be overturning	I could have overturned
you could have overturned
he could have overturned
we could have overturned
you could have overturned
they could have overturned	I could have been overturning
you could have been overturning
he could have been overturning
we could have been overturning
you could have been overturning
they could have been overturning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't overturn
you couldn't overturn
he couldn't overturn
we couldn't overturn
you couldn't overturn
they couldn't overturn 	I couldn't be overturning
you couldn't be overturning
he couldn't be overturning
we couldn't be overturning
you couldn't be overturning
they couldn't be overturning	I couldn't have overturned
you couldn't have overturned
he couldn't have overturned
we couldn't have overturned
you couldn't have overturned
they couldn't have overturned	I couldn't have been overturning
you couldn't have been overturning
he couldn't have been overturning
we couldn't have been overturning
you couldn't have been overturning
they couldn't have been overturning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I overturn?
could you overturn?
could he overturn?
could we overturn?
could you overturn?
could they overturn? 	could I be overturning?
could you be overturning?
could he be overturning?
could we be overturning?
could you be overturning?
could they be overturning? 	could I have overturned?
could you have overturned?
could he have overturned?
could we have overturned?
could you have overturned?
could they have overturned? 	could I have been overturning?
could you have been overturning?
could he have been overturning?
could we have been overturning?
could you have been overturning?
could they have been overturning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I overturn?
couldn't you overturn?
couldn't he overturn?
couldn't we overturn?
couldn't you overturn?
couldn't they overturn? 	couldn't I be overturning?
couldn't you be overturning?
couldn't he be overturning?
couldn't we be overturning?
couldn't you be overturning?
couldn't they be overturning? 	couldn't I have overturned?
couldn't you have overturned?
couldn't he have overturned?
couldn't we have overturned?
couldn't you have overturned?
couldn't they have overturned? 	couldn't I have been overturning?
couldn't you have been overturning?
couldn't he have been overturning?
couldn't we have been overturning?
couldn't you have been overturning?
couldn't they have been overturning?