2. He (drive) all day, so he was very tired when he arrived.

Решение:

2. He (drive) all day, so he was very tired when he arrived.

• had been driving. Объяснение: Действие (вождение) продолжалось в течение длительного времени до момента в прошлом (прибытие), и это действие стало причиной другого состояния (усталости). Используем Past Perfect Continuous.

Ответ: He had been driving all day, so he was very tired when he arrived.