1/

(-) They didn't decide to leave soon

(?) Did they decide to leave soon?

2/

(-) There were not any homeless people here ten years ago

(?) Were there any homeless people here ten years ago?

3/

(-) Tom's grandfather didn't use to be a soilder 

(?) Did Tom's grandfather use to be a soilder?

4/

(-) My teacher didn't start teaching here 6 years ago.

(?) Did my teacher start teaching here 6 years ago?

5/

(-) Jane didn't often go to school on foot three years ago.

(?) Did Jane often go to school on foot three years ago?

6/

(-) The cat didn't want to eat yesterday

(?) Did the cat want to eat yesterday?

7/

(-) The train did not arrive late yesterday.

(?) Did the train arrive late yesterday?

8/

(-) There wasn't anything left in the fridge.

(?) Was there anything left in the fridge?

=>
1. (-) They didn't decide to leave soon.
(?) Did they decide to leave soon?
2. (-) There weren't many homeless people here ten years ago.
(?) Were there many homeless people here ten years ago?
3. (-) Tom's grandfather didn't use to be a soldier.
(?) Did Tom's grandfather use to be a soldier?
4. (-) My teacher didn't start learning here 6 years ago.
(?) Did your teacher start teaching here 6 years ago?
5. (-) Jane didn't go to school on foot 3 years ago.
(?) Did Jane often go to school on foot 3 years ago?
6. (-) The cat didn't want to eat yesterday.
(?) Did the cat want to eat yesterday?
7. (-) The train didn't arive late yesterday.
(?) Did the train arrive late yesterday?
8. (-) There wasn't anything left in the fridge.
(?) Was there anything left in the fridge?