The days are gone we could leave our door unlocked at night.A. whereB. whichC. whenD. whi

问题补充：

The days are gone we could leave our door unlocked at night.

A. where

B. which

C. when

D. while

答案：

A. where

B. which

(答案→)C. when

D. while

解析：考查分割式定语从句。先行词为the days，谓语是are gone，后面的从句不缺少主语或宾语，缺少时间状语，所以使用关系副词。故选C。