有人问到这样一道选择题：

(1)It was very difficult to build such a great wall in the old _____.

A. year　B. time　C. days　D. day

答案是A，但我觉得应选C，对吗？

你是对的。in the old days是一现成说法，“昔日，旧时”，再如：

(2)He told us about his hard life in the old days.

in the old year的意思是“刚过去的一年或即将过去的这一年”，与句意不合，故不可选。