1.

(-) He didn't write a book.

(?) Did he write a book?

2.

(-) She wasn't my boss.

(?) Was she your boss?

3.

(+) They build a new house.

(?) Did they build a new house?

4.

(+) I wasn’t at the concert last Sunday.

(?) Were you at the concert last Sunday?

5.

(+) I bought clothes in this little shop.

(-) I didn't buy clothes in this little shop.

6. 

(+) They were born in Korea.

(-) They weren't born in Korea.