It was on May 12, 2008 the Wenchuan Earthquake happened.
A. when
B. which
C. since
D. that
网友回答
A. when
B. which
C. since
(答案→)D. that
解析：考查强调句型。强调句型的基本结构：it is/was被强调成分that/who.其它成分；强调句型最大的特点是把it is/was…that/who…去掉句子仍然成立。本题强调的是时间状语on May 12.2008;句意：在2008年5月12号，汶川地震发生了。故D正确。