English verb conjugation
COULD COST

Irregular verb: cost - cost - cost

Affirmation

Simple form	V-ing form
I could cost you could cost she could cost we could cost you could cost they could cost	I could be costing you could be costing she could be costing we could be costing you could be costing they could be costing
Perfect	V-ing perfect
I could have cost you could have cost she could have cost we could have cost you could have cost they could have cost	I could have been costing you could have been costing she could have been costing we could have been costing you could have been costing they could have been costing

Negation

Simple form	V-ing form
I couldn't cost you couldn't cost she couldn't cost we couldn't cost you couldn't cost they couldn't cost	I couldn't be costing you couldn't be costing she couldn't be costing we couldn't be costing you couldn't be costing they couldn't be costing
Perfect	V-ing perfect
I couldn't have cost you couldn't have cost she couldn't have cost we couldn't have cost you couldn't have cost they couldn't have cost	I couldn't have been costing you couldn't have been costing she couldn't have been costing we couldn't have been costing you couldn't have been costing they couldn't have been costing

Interrogative form

Simple form	V-ing form
could I cost? could you cost? could she cost? could we cost? could you cost? could they cost?	could I be costing? could you be costing? could she be costing? could we be costing? could you be costing? could they be costing?
Perfect	V-ing perfect
could I have cost? could you have cost? could she have cost? could we have cost? could you have cost? could they have cost?	could I have been costing? could you have been costing? could she have been costing? could we have been costing? could you have been costing? could they have been costing?

Interro-negative form

Simple form	V-ing form
couldn't I cost? couldn't you cost? couldn't she cost? couldn't we cost? couldn't you cost? couldn't they cost?	couldn't I be costing? couldn't you be costing? couldn't she be costing? couldn't we be costing? couldn't you be costing? couldn't they be costing?
Perfect	V-ing perfect
couldn't I have cost? couldn't you have cost? couldn't she have cost? couldn't we have cost? couldn't you have cost? couldn't they have cost?	couldn't I have been costing? couldn't you have been costing? couldn't she have been costing? couldn't we have been costing? couldn't you have been costing? couldn't they have been costing?