Ответ:

1 they hadn't left for the airport before 5 o'clock.

1 had they left for the airport before 5 o'clock?

2 you hadn't fixed that camera by Tuesday.

2 had you fixed that camera by Tuesday?

3 Peter hadn't paid the electricity bill before the weekend.

3 had Peter paid the electricity bill before the weekend?

4 Wendy hadn't shown me her fancy dress for the New year party before.

4 had Wendy shown me her fancy dress for the New year party before?

5 it hadn't stopped snowing by 9 o'clock.

5 had it stopped snowing by 9 o'clock?

Make the sentences negative and interrogative.

1. They had left for the airport before 5 o'clock.

They hadn't left for the airport before 5 o'clock.

Had they left  for the airport before 5 o'clock?

2. You had fixed that camera by Tuesday.

You hadn't fixed that camera by Tuesday.

Had you fixed that camera by Tuesday?

3. Peter had paid the electricity bill before the weekend.

Peter hadn't paid the electricity bill before the weekend.

Had Peter paid the electricity bill before the weekend?

4. Wendy had shown me her fancy dress for the New Year party before.

Wendy hadn't shown me her fancy dress for the New Year party before.

Had Wendy shown me her fancy dress for the New Year party before?

5. It had stopped snowing by 9 o'clock.

It hadn't stopped snowing by 9 o'clock.

Had it stopped snowing by 9 o'clock?