Resposta :
1 - Maysa was playing video game when I left
2 - He was watching TV when his mother arrived
3 - I was studying while my father was working
4 - We were listening to music when the lights went out.
5 - I was talking about games with Helen.
6 - I think the car was making noise because it's old.
7 - He was leaving the office when Mary called him.
8 - I was picking some fruits at supermarket while my sister was waiting at the car.
9 - They did great at the competition.
10 - She did an awful job at hiding her blush.
*Se tiver algum erro, me desculpe; fiquei na dúvida se era pra responder com past continuous E simple past ou só com o primeiro, então fiz do modo que achei certo. Bons estudos!!!