We students should treasure the short senior school’s study life of three years. Once , the opportunity can’t get back.
A. losing
B. was lost
C. lost
D. being lost
网友回答
A. losing
B. was lost
(答案→)C. lost
D. being lost
解析：考查状语从句的省略：句意：我们每个学生应该珍惜短暂的三年高中学习生活，一旦失去了，机会不再来。Once引导的是条件状语从句，是省略句，完整的是once the short senior school’s study life is lost，主从句主语一致的时候，主语和be动词可以省略，选C。