The four years, from 1860 to 1864 Lincoln spent fighting for freedom of the slaves is the time the American people will never forget.
A. when; when
B. which ; that
C. when; which
D. which; when
网友回答
A. when; when
(答案→)B. which ; that
C. when; which
D. which; when
解析：第一空填一个关系代词which, 在定语从句中作spent的宾语;第二空所填的that在定语从句中作forget的宾语.