don't I cost? don't you cost? doesn't she cost? don't we cost? don't you cost? don't they cost?
Present continuous
am I not costing? aren't you costing? isn't she costing? aren't we costing? aren't you costing? aren't they costing?
Preterite
didn't I cost? didn't you cost? didn't she cost? didn't we cost? didn't you cost? didn't they cost?
Preterite continuous
wasn't I costing? weren't you costing? wasn't she costing? weren't we costing? weren't you costing? weren't they costing?
Present perfect
haven't I cost? haven't you cost? hasn't she cost? haven't we cost? haven't you cost? haven't they cost?
Present perfect continuous
haven't I been costing? haven't you been costing? hasn't she been costing? haven't we been costing? haven't you been costing? haven't they been costing?
Pluperfect
hadn't I cost? hadn't you cost? hadn't she cost? hadn't we cost? hadn't you cost? hadn't they cost?
Pluperfect continuous
hadn't I been costing? hadn't you been costing? hadn't she been costing? hadn't we been costing? hadn't you been costing? hadn't they been costing?
Future
won't I cost? won't you cost? won't she cost? won't we cost? won't you cost? won't they cost?
Future continuous
won't I be costing? won't you be costing? won't she be costing? won't we be costing? won't you be costing? won't they be costing?
Future perfect
won't I have cost? won't you have cost? won't she have cost? won't we have cost? won't you have cost? won't they have cost?
Future perfect continuous
won't I have been costing? won't you have been costing? won't she have been costing? won't we have been costing? won't you have been costing? won't they have been costing?
Conditional
Present
wouldn't I cost? wouldn't you cost? wouldn't she cost? wouldn't we cost? wouldn't you cost? wouldn't they cost?
Present continuous
wouldn't I be costing? wouldn't you be costing? wouldn't she be costing? wouldn't we be costing? wouldn't you be costing? wouldn't they be costing?
Past
wouldn't I have cost? wouldn't you have cost? wouldn't she have cost? wouldn't we have cost? wouldn't you have cost? wouldn't they have cost?
Past continuous
wouldn't I have been costing? wouldn't you have been costing? wouldn't she have been costing? wouldn't we have been costing? wouldn't you have been costing? wouldn't they have been costing?