Question

3. Make negative(-), positive(+) sentences and questions(?)
1) The students had finished the dinner two hours before that
2) She had found her bag.
3) The driver had cleaned the car twice before.
4) Sue and Tom had already flown to Moscow
5) The boy had just listened to the radio.

Answer 1

1)
(+) The students had finished the dinner 2 hours before that.
(-) The student had not (hadn't) finished the dinner 2 hours before that.
(?) Did the students were finishing the dinner 2 hours before that?
2) 
(+) She had found her bag.
(-) She had't find her bag.
(?) Did she find her bag?
3)
(+) The driver had cleaned the car twice before.
(-) The driver hadn't cleaned the car twice before.
( я очень сомневаюсь)