Hello,
I know we should normally use 'while' as a conjunction introducing the past continuous, for example:
- I fell down while I was running to school.
- While I was looking through my old photos, I came across a photo of my great-grandfather.
- Sometimes we can see 'when' used instead of 'while'. Is it also ok?:
- I fell down when I was running to school.
- When I was looking through my old photos, I came across a photo of my great-grandfather.
Thank you for your help.