There were signs here and there,____visitors to look out for_____rocks.

题目

There were signs here and there,____visitors to look out for_____rocks.
A.warning:fallen B.warning:falling C.warned:fallling D.to warn:fallen

答案

B.warning; falling
第一个现在分词warning作后置定语,相当于定语从句：which warned visitors...,表示“告示牌上写着警告”.
第二个现在分词falling 也作定语,表示”在下落过程中的“.