English verb conjugation
COULD FORM

Regular verb: form - formed - formed

Affirmation

Simple form	V-ing form
I could form you could form he could form we could form you could form they could form	I could be forming you could be forming he could be forming we could be forming you could be forming they could be forming
Perfect	V-ing perfect
I could have formed you could have formed he could have formed we could have formed you could have formed they could have formed	I could have been forming you could have been forming he could have been forming we could have been forming you could have been forming they could have been forming

Negation

Simple form	V-ing form
I couldn't form you couldn't form he couldn't form we couldn't form you couldn't form they couldn't form	I couldn't be forming you couldn't be forming he couldn't be forming we couldn't be forming you couldn't be forming they couldn't be forming
Perfect	V-ing perfect
I couldn't have formed you couldn't have formed he couldn't have formed we couldn't have formed you couldn't have formed they couldn't have formed	I couldn't have been forming you couldn't have been forming he couldn't have been forming we couldn't have been forming you couldn't have been forming they couldn't have been forming

Interrogative form

Simple form	V-ing form
could I form? could you form? could he form? could we form? could you form? could they form?	could I be forming? could you be forming? could he be forming? could we be forming? could you be forming? could they be forming?
Perfect	V-ing perfect
could I have formed? could you have formed? could he have formed? could we have formed? could you have formed? could they have formed?	could I have been forming? could you have been forming? could he have been forming? could we have been forming? could you have been forming? could they have been forming?

Interro-negative form

Simple form	V-ing form
couldn't I form? couldn't you form? couldn't he form? couldn't we form? couldn't you form? couldn't they form?	couldn't I be forming? couldn't you be forming? couldn't he be forming? couldn't we be forming? couldn't you be forming? couldn't they be forming?
Perfect	V-ing perfect
couldn't I have formed? couldn't you have formed? couldn't he have formed? couldn't we have formed? couldn't you have formed? couldn't they have formed?	couldn't I have been forming? couldn't you have been forming? couldn't he have been forming? couldn't we have been forming? couldn't you have been forming? couldn't they have been forming?