Ответ:

1. was lying, started

2. were you doing, во втором пропуске подходят оба, так что выбирай любой

3. saw, was dancing

4. were having, rang

5. was leaving, knocked

6. was driving, saw

7. broke, was climbing

8. studying

Объяснение:

1. I was lying on the beach when suddenly it started raining. - Я лежал на пляже, как внезапно начался сильный дождь.

2. What were you doing when I called you at four o 'clock this afternoon? - Что ты делал, когда я звонил тебе в четыре часа дня?

3. The first time I saw my boyfriend , he was dancing at a party. - Я впервые увидела своего парня, когда он танцевал на вечеринке.

4. We were having lunch when the phone rang. - Мы обедали, когда зазвонил телефон.

5. It was a beautiful morning.I was leaving home to go to work. Suddenly the postman knocked on the front door. - Было прекрасное утро. К сожалению я уходил из дома на работу.

6. When my mother was driving to work yesterday , she saw her old friend from school. - Когда моя мама ехала на работу вчера, она видела своего старого школьного друга

7. Molly broke her leg when she was climbing a tree. - Молли сломала ногу, когда лазала по дереву

8. Was Susan studying yesterday at 8 p.m.? - Сьюзан занималась вчера в 8 вечера?