The most important thing we should pay attention to is the first thing I have said.
A. which; that
B. that; which
C. which; which
D. that; that
网友回答
A. which; that
B. that; which
C. which; which
(答案→)D. that; that
解析：先行词分别被形容词最高级和序数词修饰，故关系代词都选that。