问题
选择题
It was on July 1, 2006 ___ Qinghai-Tibet railway began operation, ____ is a symbolic project in China’s West Development Strategy．
A．when; that
B．that; when
C．which; when
D．that; which
答案
答案：D
第一个空是强调句型，因此填that；第二个空是由which引导的非限制性定语从句。故选D。