1.
(-) He wasn't planting trees...
(?) Was he planting trees... ? → Yes, he was./ No, he wasn't.
2.
(-) They weren't working...
(?) Were they working... ? → Yes, they were./ No they weren't.
3.
(-) She wasn't painting...
(?) Was she panting... ? → Yes, she was./ No, she wasn't.
4.
(-) Anne wasn't riding...
(?) Was Anne riding... ? → Yes, she was./ No, she wasn't.
5.
(-) He wasn't typing...
(?) Was he typing... ? → Yes, he was./ No, he wasn't.