Here are the correct forms of the verbs for each sentence:

7. She met him while she **was traveling** on a train.
8. While the woman was getting off the bus, she **fell down**.
9. The thief **broke** into while we were sleeping.
10. Lan took a photo while I **was not looking**.
11. While my mum was working in the garden, she **hurt** her back.
12. We were living in Hanoi when our old aunt **died**.
13. When I got up this morning it **was raining** heavily.