Theydideverythingintheirpowertosavethebuildingdatingba...

問題詳情：

 They did everything in their power to save the building dating back to the Qing Dynasty, but their efforts were _______.

A. in turn               B. in time           C. in vain           D. in need

【回答】

C

知識點：介詞

題型：選擇題