I've worked here since I__________ Harvard Business School.

I've worked here since I__________ Harvard Business School.
A、leave
B、left
C、have left
D、had left
【正确答案】：B
【题目解析】：since前如果谓语动词为现在完成式，since后谓语动词为过去式。B项是正确的。句意为:“自从我离开哈佛商学院就一直在这儿工作。”