Nobody believed a 92-year-old man could run a marathon he passed the finishing line. People of all ages can challenge themselves.
A. if
B. since
C. until
D. unless
网友回答
A. if
B. since
(答案→)C. until
D. unless
解析：考查状语从句连接词。句意：没有人相信一个92岁的老人能参加马拉松，直到他跑到了终点线。每个年龄段的人都可以挑战一下自己。not...until...直到......才......。If如果，表条件；since自从；unless除非。故选C。