【题目】The young couple _______ as volunteer teachers for a whole year during their stay in Yunnan.
A. have worked B. had worked
C. worked D. have been working
在线课程【答案】C
【解析】
考查时态。句意：在云南期间，这对年轻的夫妻做了一整年的志愿者。根据句意可知他们是在云南期间做志愿者的，使用一般过去时描述过去发生的事情，并没有延续到现在，也没有表现出对现在的影响，故C项正确。