I can never forget the days we worked together and the days we spent happily together.
A. for which; that
B. which; when
C. when; which
D. on which; when
网友回答
A. for which; that
B. which; when
(答案→)C. when; which
D. on which; when
解析：考查定语从句，先行词是the days，第一空填when，因为定语从句中缺少时间状语，第二空填which，因为定语从句中缺乏宾语，句意：我永远不能忘记我们一起工作的日子和我们一起快乐度过的日子。选C。