Ответ: 1. lost, was changing; 2. was looking
He lost his umbrella at the underground station when he was changing the lines.
Он потерял свой зонт на станции метро, когда пересаживался на другую линию.
I was busy last night, I was looking for my jacket at the lost property.
Я был занят вчера вечером, я искал мою куртку в бюро находок.
Ответ: 1. lost, was changing; 2. was looking