---- How long was it you finally reached your goal of being a doctor?
---- Five years.
A. before
B. since
C. when
D. until
网友回答
(答案→)A. before
B. since
C. when
D. until
解析：本题实际上考察的是固定句式：固定句式：It /That/This is the...time that sb have done sth；It /That/This was the...time that sb had done sth。“这是某人第几次做某事的时候了”；结合日常生活实际，能够计算到这是第几次做某事，表明该动作已经发生，因此，要用完成时态——主句用现在时，从句用现在完成时；主句用过去时，从句用过去完成时。只不过本句是一个特殊疑问句，对其中的一段时间进行提问。句义：多久以后你才实现你做医生的目标？—5年。故A正确。