—So when did you meet Joan?
—It was last Sunday she came to visit my sister.
A. that
B. since
C. when
D. Before
网友回答
A. that
B. since
(答案→)C. when
D. Before
解析：考查从句辨析。为避免与第一句重复，答语句尾省略了that I met Joan，答语是一个强调句，强调的是时间状语last Sunday，强调句中包含了一个when引导的定语从句，故选C。