(·厦门质检)Hardly twelve when they realized that it was too late to catch the last train.

问题补充：

(·厦门质检)Hardly twelve when they realized that it was too late to catch the last train.

A. the clock had struck

B. the clock had been struck

C. had the clock been struck

D. had the clock struck

答案：

A. the clock had struck

B. the clock had been struck

C. had the clock been struck

(答案→)D. had the clock struck

解析：hardly...when...表示“一……就……”。否定副词hardly放在句首时，主句要用部分倒装。时钟敲响应用主动语态。故答案为D项。