The old man often looked back on the past days he worked hard to make a living.A. whichB

问题补充：

The old man often looked back on the past days he worked hard to make a living.

A. which

B. when

C. where

D. that

答案：

A. which

(答案→)B. when

C. where

D. that

解析：B考查定语从句。句意：这个老人经常回顾他过去辛苦谋生的日子。分析句子成分可知，先行词为the past days，空处在定语从句中充当时间状语，故用when引导。