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