问题补充:
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
答案:
A. in turn
B. in time
(答案→)C. in vain
D. in need
解析:
试题分析:句意:他们在能力范围内尽一切努力去挽救始于清朝时期的建筑,但是他们的努力是徒劳的。A轮流;B及时;C徒劳;D需要。根据but可知后面和前面内容是转折关系,选C。