English verb conjugation
COULD INVENT

Regular verb: invent - invented - invented

Affirmation

Simple form	V-ing form
I could invent you could invent he could invent we could invent you could invent they could invent	I could be inventing you could be inventing he could be inventing we could be inventing you could be inventing they could be inventing
Perfect	V-ing perfect
I could have invented you could have invented he could have invented we could have invented you could have invented they could have invented	I could have been inventing you could have been inventing he could have been inventing we could have been inventing you could have been inventing they could have been inventing

Negation

Simple form	V-ing form
I couldn't invent you couldn't invent he couldn't invent we couldn't invent you couldn't invent they couldn't invent	I couldn't be inventing you couldn't be inventing he couldn't be inventing we couldn't be inventing you couldn't be inventing they couldn't be inventing
Perfect	V-ing perfect
I couldn't have invented you couldn't have invented he couldn't have invented we couldn't have invented you couldn't have invented they couldn't have invented	I couldn't have been inventing you couldn't have been inventing he couldn't have been inventing we couldn't have been inventing you couldn't have been inventing they couldn't have been inventing

Interrogative form

Simple form	V-ing form
could I invent? could you invent? could he invent? could we invent? could you invent? could they invent?	could I be inventing? could you be inventing? could he be inventing? could we be inventing? could you be inventing? could they be inventing?
Perfect	V-ing perfect
could I have invented? could you have invented? could he have invented? could we have invented? could you have invented? could they have invented?	could I have been inventing? could you have been inventing? could he have been inventing? could we have been inventing? could you have been inventing? could they have been inventing?

Interro-negative form

Simple form	V-ing form
couldn't I invent? couldn't you invent? couldn't he invent? couldn't we invent? couldn't you invent? couldn't they invent?	couldn't I be inventing? couldn't you be inventing? couldn't he be inventing? couldn't we be inventing? couldn't you be inventing? couldn't they be inventing?
Perfect	V-ing perfect
couldn't I have invented? couldn't you have invented? couldn't he have invented? couldn't we have invented? couldn't you have invented? couldn't they have invented?	couldn't I have been inventing? couldn't you have been inventing? couldn't he have been inventing? couldn't we have been inventing? couldn't you have been inventing? couldn't they have been inventing?