单选题 Dr. Kim ______ for 12 years on the Board of New York University by the time she resigns next February.
A. been served
B. had served
C. has served
D. will have served

【正确答案】 D

【答案解析】中级问题一看到for 12 years，可能会倾向于选择现在完成时C选项。但后半句说到“明年2月份退休时就满12年”，所以现在还没有达到12年。因此要用将来完成时。