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