英语 高三 选择题 简单

过去完成时的运用 — 英语选择题

人教版·英语(高中) UNIT 4 ADVERSITY AND COURAGE AI 三重审校通过

题目
Choose the correct option: The explorers were exhausted because they ___ through the storm for two days before they found the cave. A. walked B. had walked C. have walked D. were walking