Ответ:

25 Linda had been trying to find a present for her mum for over an hour before she finally saw something nice to buy her.

26 William had already heard the news when I called to tell him.

27 While Emma was doing her homework, her brother was playing music loudly, and she couldn't concentrate.

28 Nathan came across a photo of his great-grandfather as he was looking through some old things.

29 Helen was exhausted because she had been jogging for two hours.