—All the building materials have been washed away.
—So I have heard. But there was no sign a heavy rain was on the way last night.
A. when
B. that
C. which
D. If
网友回答
A. when
(答案→)B. that
C. which
D. If
解析：主要测试同位语从句。no sign与后面的句子为同位关系。译文：------所有的检出材料都被冲走了。------我已经听说了。但是昨晚并没有将要下大雨的迹象啊。