could invert
Regular verb: invert - inverted- inverted

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could invert
you could invert
she could invert
we could invert
you could invert
they could invert 	I could be inverting
you could be inverting
she could be inverting
we could be inverting
you could be inverting
they could be inverting	I could have inverted
you could have inverted
she could have inverted
we could have inverted
you could have inverted
they could have inverted	I could have been inverting
you could have been inverting
she could have been inverting
we could have been inverting
you could have been inverting
they could have been inverting	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't invert
you couldn't invert
she couldn't invert
we couldn't invert
you couldn't invert
they couldn't invert 	I couldn't be inverting
you couldn't be inverting
she couldn't be inverting
we couldn't be inverting
you couldn't be inverting
they couldn't be inverting	I couldn't have inverted
you couldn't have inverted
she couldn't have inverted
we couldn't have inverted
you couldn't have inverted
they couldn't have inverted	I couldn't have been inverting
you couldn't have been inverting
she couldn't have been inverting
we couldn't have been inverting
you couldn't have been inverting
they couldn't have been inverting	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I invert?
could you invert?
could she invert?
could we invert?
could you invert?
could they invert? 	could I be inverting?
could you be inverting?
could she be inverting?
could we be inverting?
could you be inverting?
could they be inverting? 	could I have inverted?
could you have inverted?
could she have inverted?
could we have inverted?
could you have inverted?
could they have inverted? 	could I have been inverting?
could you have been inverting?
could she have been inverting?
could we have been inverting?
could you have been inverting?
could they have been inverting? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I invert?
couldn't you invert?
couldn't she invert?
couldn't we invert?
couldn't you invert?
couldn't they invert? 	couldn't I be inverting?
couldn't you be inverting?
couldn't she be inverting?
couldn't we be inverting?
couldn't you be inverting?
couldn't they be inverting? 	couldn't I have inverted?
couldn't you have inverted?
couldn't she have inverted?
couldn't we have inverted?
couldn't you have inverted?
couldn't they have inverted? 	couldn't I have been inverting?
couldn't you have been inverting?
couldn't she have been inverting?
couldn't we have been inverting?
couldn't you have been inverting?
couldn't they have been inverting?