问题补充：
Was it in the factory you worked five years ago you learned the technique?
A. that; where
B. where; when
C. where; where
D. where; that
答案：
A. that; where
B. where; when
C. where; where
(答案→)D. where; that
解析：从整个句子来分析，本题的主干是Was it in the factory you worked you learned the technique?这一强调结构，you worked five years ago 是定语从句，限定the factory。
