=>
III/
1. were building
2. was driving
3. was chatting/was teaching
4. was watching
5. was preparing
6. were you doing
7. were you going
8. were not going
9. was not doing
10. was reading/was playing
IV/
1. (-) He wasn't planting trees in the garden at 4 pm yesterday.
(?) Was he planting trees in the garden at 4 pm yesterday?
2. (-) They weren't working when she came yesterday.
(?) Were they working when she came yesterday?
3. (-) She wasn't painting a picture while her mother was making a cake.
(?) Was she painting a picture while her mother was making a cake?
4. (-) Anne wasn't riding her bike to school when Peter saw her yesterday.
(?) Was Anne riding her bike to school when Peter saw her yesterday?
5. (-) He wasn't typing a letter when his boss went into the room.
(?) Was he typing a letter when his boss went into the room?

III. 1. were building

2. was driving

3. was chatting-was teaching

4. was watching

5. was preparing

6. was you doing

7. was you going

8. weren't going

9. wasn't doing

10. was reading

IV. 1. He wasn't planting trees in the garden at 4 pm yesterday.

Was he planting trees in the garden at 4 pm yesterday ?

2. They weren't working when she came yesterday.

Were they working when she came yesterday?

3. She wasn't painting a picture while her mother was making a cake.

Was she painting a picture while her mother was making a cake?

4. Anna wasn't riding her bike to school when Peter saw her yestetday.

Was Anna riding her bike to school....yesterday?

5. He wasn't typing a letter when his boss went into the room.

Was he typing a letter when his boss went into the room