English verb conjugation
COULD COST

Irregular verb: cost - cost - cost

Affirmation

Simple form	V-ing form
I could cost you could cost he could cost we could cost you could cost they could cost	I could be costing you could be costing he 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 he 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 he 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 he 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 he 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 he 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 he 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 he cost? could we cost? could you cost? could they cost?	could I be costing? could you be costing? could he 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 he 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 he 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 he 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 he 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 he 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 he have been costing? couldn't we have been costing? couldn't you have been costing? couldn't they have been costing?