1. He *was eating* when the phone rang. (Dica: ação contínua antes de outra no passado)
2. They *had been studying* for hours before the exam started. (Dica: ação prolongada antes de um ponto no passado)
3. She *had been working* at the company for five years by 2019. (Dica: duração da ação passada anterior a outra)
4. We *were walking* in the park when it began to rain. (Dica: ação em progresso no passado)
5. I *had been waiting* for the bus for 30 minutes before it arrived. (Dica: ação contínua anterior a outra no passado)
6. The children *were playing* outside when their mother called them. (Dica: ação em andamento interrompida)
7. He *had been reading* the book before he fell asleep. (Dica: ação prolongada anterior a outra)
8. You *were talking* to me while I was cooking. (Dica: duas ações simultâneas no passado)
9. She *had been feeling* ill before going to the doctor. (Dica: estado contínuo anterior a outro evento)
10. We *were listening* to music when the power went out. (Dica: ação em progresso no passado)

1. They *had been traveling* for days before they reached the city. (Dica: ação prolongada concluída antes de outra)
2. I *was studying* when you called me last night. (Dica: ação em andamento interrompida)
3. She *had been practicing* the piano before the recital. (Dica: ação repetida antes de outro evento)
4. We *were cooking* dinner when the guests arrived. (Dica: ação contínua no passado)
5. He *had been feeling* tired all day before he rested. (Dica: estado contínuo anterior a outra ação)
6. You *were watching* TV while I was cleaning the house. (Dica: ações simultâneas no passado)
7. The dog *had been barking* before the doorbell rang. (Dica: ação prolongada anterior a outra)
8. I *was writing* a letter when the electricity went off. (Dica: ação interrompida no passado)
9. They *had been living* in that town for years before moving. (Dica: duração de uma ação passada anterior)
10. She *was talking* on the phone when I arrived. (Dica: ação em progresso no passado)