Here are the sentences rewritten in the passive voice:

1. Did you see that? Our neighbour was being arrested by the police.
2. The cause of the accident is being investigated by the police.
3. A new hospital was being built when I was there.
4. Is the old shopping mall being demolished at the moment?
5. The trees weren’t being cut down when I saw them.
6. I was sure that my mobile was being used by someone else.
7. Are books being sold at reduced prices?
8. I didn’t want to look when our team was being beaten.
9. The chickens are being fed by my mum.
10. Because of the pandemic, meetings are being held online.