could overturn
Regular verb: overturn - overturned- overturned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could overturn
you could overturn
she could overturn
we could overturn
you could overturn
they could overturn 	I could be overturning
you could be overturning
she could be overturning
we could be overturning
you could be overturning
they could be overturning	I could have overturned
you could have overturned
she 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
she 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
she 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
she 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
she 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
she 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 she overturn?
could we overturn?
could you overturn?
could they overturn? 	could I be overturning?
could you be overturning?
could she be overturning?
could we be overturning?
could you be overturning?
could they be overturning? 	could I have overturned?
could you have overturned?
could she 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 she 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 she 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 she 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 she 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 she have been overturning?
couldn't we have been overturning?
couldn't you have been overturning?
couldn't they have been overturning?