9. Kate..... (go) to school when she met her old friend.

Kate was going to school when she met her old friend. / Kate went to school when she met her old friend. *Explanation:* Either past continuous or past simple can be used here, depending on the nuance. Past continuous suggests that she was in the process of going to school when she encountered her friend. Past simple simply indicates she went to school and that's where she met her friend.