Verb be in past. Short answers.
1. Were they happy with the results?  No, they did not.  No, they aren’t.  No, they did not.  No, they were not. 2. Was it wrong?  No, it wasn’t.  No, it isn’t.  No, it doesn’t.  No, it didn’t. 3. Was he your accountant?  No, he isn’t.  No, he don’t.  No, he doesn’t.  No, he wasn’t. [...] MORE