【题目】----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
在线课程【答案】B
【解析】
试题分析：句意: 所有的建筑材料都被冲走了；我也听说这样。但是没有迹象说昨晚要来大雨。sign后是同位语从句说明sign的内容，that没有实在意义，又不可缺少。故选B。