Past perfect/past perfect continuous
when we came back home, the children (sleep) for two hours.
tina (just, go) home when i phoned her.
i was glad to meet ted again. i (not see) him for ages.
mom was tired yesterday. she (clean) the house all day.
the boys were out of breath. they (run) a marathon.
mark told me that he (buy) a new suit.
when i arrived, lucy (lie) in bed with temperature since lunchtime.
my mom (already cook) dinner when i returned home.
sean explained why he (write) an essay.
there were puddles in the streets as it (rain) all night.
i (wait) for lena at the disco but she didn’t turn up.
they (visit) the same restaurant for years before they found a better one.
sam (want) to go to the wedding but he couldn’t take a day off work.
jack said he (book) tickets for the concert.
mike said they (stay) at the airport for two days because of the delay of their flight.
andrew said (never be) to china before.
we (eat) for half an hour when dan finally joined us.
mary insisted that she (take) the ring from the drawer.
i (join) the golf club before martin did it.
we were very tired at the end of the trip. we (drive) for ten hours.

Когда мы вернулись домой, дети спали уже два часа.
Дети уже спали два часа, когда мы вернулись домой.

Чтобы правильно использовать времена Past Perfect и Past Perfect Continuous, нужно понимать их значения и правила образования.

Past Perfect (Прошедшее совершенное время) используется, чтобы выразить состояние или действие, которое произошло до определенного времени в прошлом. В этом случае, временной отсчет происходит от того момента, к которому мы относимся в предложении. Используется образец "had + третья форма глагола".

Past Perfect Continuous (Прошедшее совершенное продолженное время) используется, чтобы выразить длительное действие, которое началось до определенного времени в прошлом и продолжалось до него. Образуется с помощью "had been + -ing форма глагола".

Теперь пошагово решим предложения:

1. When we came back home, the children had slept for two hours.
Когда мы вернулись домой, дети уже спали два часа.
Мы используем Past Perfect, потому что спящие дети - это состояние, которое продолжалось до того момента, когда мы пришли домой.

2. Tina had just gone home when I phoned her.
Тина только что ушла домой, когда я ей позвонил.
Мы используем Past Perfect, потому что действие "ушла домой" произошло до момента звонка.

3. I was glad to meet Ted again. I hadn't seen him for ages.
Я был рад встретить Теда опять. Я давно его не видел.
Мы используем Past Perfect, потому что длительность его отсутствия была до момента встречи.

4. Mom was tired yesterday. She had cleaned the house all day.
Мама была уставшая вчера. Она убирала весь день.
Мы используем Past Perfect, так как "убирала" - это действие, которое происходило перед моментом, описываемым в предложении.

5. The boys were out of breath. They had been running a marathon.
Мальчики задыхались. Они пробежали марафон.
Мы используем Past Perfect Continuous, потому что длительное действие "бежали" началось до момента описания и продолжалось до него.

Продолжаем решать остальные предложения по аналогии с предыдущими примерами.

6. Mark told me that he had bought a new suit.
7. When I arrived, Lucy had been lying in bed with temperature since lunchtime.
8. My mom had already cooked dinner when I returned home.
9. Sean explained why he had been writing an essay.
10. There were puddles in the streets as it had been raining all night.
11. I had been waiting for Lena at the disco but she didn’t turn up.
12. They had been visiting the same restaurant for years before they found a better one.
13. Sam wanted to go to the wedding but he couldn’t take a day off work.
14. Jack said he had booked tickets for the concert.
15. Mike said they had been staying at the airport for two days because of the delay of their flight.
16. Andrew said he had never been to China before.
17. We had been eating for half an hour when Dan finally joined us.
18. Mary insisted that she had taken the ring from the drawer.
19. I had joined the golf club before Martin did it.
20. We were very tired at the end of the trip. We had been driving for ten hours.