问题
选择题
There were signs here and there, _____ visitors to look out for ______ rocks.
A．warning; fallen
B．warned; falling
C．to warn; fallen
D．warning; falling
答案
答案：D
D考查非谓语动词用法。signs与warnde 关系为主动故用现在分词；for后接动名词，故答案为D。