14. While I (clean) the house, I (find) an old photo album.

14. While I (clean) the house, I (find) an old photo album.

В данном предложении необходимо употребить Past Continuous для действия, которое происходило в определенный момент в прошлом (while I was cleaning), и Past Simple для действия, которое прервало первое (I found).

While I was cleaning the house, I found an old photo album.

Ответ: While I was cleaning the house, I found an old photo album.