单选题 I've worked here since I ______ Harvard Business School.
A. leave B. left C. have left D. had left

【正确答案】 B
【答案解析】[解析] since前如果谓语动词为现在完成式，since后谓语动词为一般过去式。选项B是正确的。句意为：“自从我离开哈佛商学院就一直在这儿工作。”