单选题 By Christmas I ______ in this office for ten years.
A. will work B. will be working
C. will have been working D. will have worked

【正确答案】 C
【答案解析】[解析] 动词时态题。“by+时间”表示“到……时为止”，标志着本题的谓语动词应采用完成时态，故可排除A和B；题干表明“到那时我还要继续工作下去”，故C为将来完成进行时，正符合句意，故为答案。