Subject + was/were + V-ing.
Ann was reading a book at 5p.m. yesterday.
The children were playing hide-and-seek in the park all the morning yesterday.
Subject + was/were + not + V-ing.
Contractions: wasn't, weren't
Ann was not reading a book. = Ann wasn't reading a book.
The children were not playing hide-and-seek. = The children weren't playing hide-and-seek.
Was/were + subject + V-ing?
Was Ann reading a book? — Yes, she was.
Was Ann reading a newspaper? — No, she wasn't.
Were the children playing hide-and-seek in the park? — Yes, they were.
Were the children playing football in the park? — No, they weren't.
Question word + was/were + subject + V-ing?
What was Ann reading? — She was reading a newspaper.
Where were the children playing hide-and-seek? — They were playing in the yard.