7. We swam while David and Peter jogged by the lake. Choices: were swimming / was swimming; were jogging / was jogging.

Перевод задания: Простое прошедшее или прошедшее длительное время.

We were swimming while David and Peter were jogging by the lake.
Мы плавали, пока Дэвид и Питер бегали трусцой у озера.

Два действия происходили одновременно, поэтому используем Past Continuous: were swimming и were jogging.