答案：A

题目分析：考查倒装句型。no sooner…than…结构中的 no sooner置于句首时，其后引出部分倒装。如：No sooner had we left the house than it began to rain. 我们刚离开家就开始下雨了。No sooner had we reached the airport than the plane took off. 我们刚到机场，飞机就起飞了。该句型中一般主句用过去完成时，从句用一般过去时。