过去完成时的运用 — 英语选择题

Choose the correct option: The explorers were exhausted because they ___ through…

After weeks of polar darkness, the crew finally saw the sun. The captain wrote t…

Choose the correct option to complete the sentence: If the radio operator ___ th…

用括号内动词的适当时态填空：By the time the blizzard struck, the A…

Choose the correct option: Before the team of climbers reached the final camp, t…

By the time the rescue team finally reached the isolated camp, the climbers ___ …