1. parents were eating\ate while kids played\were playing. 2. I was listening\listened to music so I wasn't hearing\didn't hear the phone ring. 3. At 8 o'clock I was waiting\waited for my friends. 4. When I came\comed home, I saw\seed my dog lying on my bed.

Решение:

• 1. parents were eating while kids were playing. (Present Continuous для действий, происходивших в определённый момент в прошлом).
• 2. I was listening to music so I wasn't hearing the phone ring. (Present Continuous для основного действия, Past Simple для момента, когда что-то произошло или не произошло).
• 3. At 8 o'clock I was waiting for my friends. (Present Continuous для действия, происходившего в конкретный момент в прошлом).
• 4. When I came home, I saw my dog lying on my bed. (Past Simple для завершённого действия, которое прервало другое действие, или которое произошло до другого действия).