问题补充:
Thousands of years ago people discovered the phenomenon by chance, and this was the idea of the compass first came from.
A. how
B. what
C. where
D. that
答案:
A. how
B. what
(答案→)C. where
D. that
解析:考查定语从句。句中the phenomenon为下文the idea of the compass first came from的逻辑地点状语,故选C,where做from逻辑宾语,指代前文的the phenomenon。