Were they watching TV?
Yes, they were.
Was she walking the dog yesterday?
Yes, she was.
Was she talking on the phone this morning?
Yes, she was.
Was he taking out the trash last Sunday?
No, he wasn't.
Was she walking the dog last Saturday?
No, she wasn't.
Were they working on the computer two hours ago?
Yes, they were.
Was she mowing the lawn?
No, she wasn't.
Were they doing the laundry?
Yes, they were.
Was he working on the computer?
No, he wasn't.
Was she doing the dishes yesterday morning?
Yes, she was.