the rain falling so frequently ,it becomes more and more difficult to carry on_______ the rain falling so frequently ,it becomes more and more difficult to carry on the rescue work.A.since B.with C.as D.for\应该选B.为什么不是A?众所周知的

the rain falling so frequently ,it becomes more and more difficult to carry on_______ the rain falling so frequently ,it becomes more and more difficult to carry on the rescue work.A.since B.with C.as D.for\应该选B.为什么不是A?众所周知的
the rain falling so frequently ,it becomes more and more difficult to carry on
_______ the rain falling so frequently ,it becomes more and more difficult to carry on the rescue work.
A.since B.with C.as D.for\
应该选B.为什么不是A?众所周知的原因“由于雨下的很频繁,营救工作很难进行”

the rain falling so frequently ,it becomes more and more difficult to carry on_______ the rain falling so frequently ,it becomes more and more difficult to carry on the rescue work.A.since B.with C.as D.for\应该选B.为什么不是A?众所周知的
since 引导一个句子,如果用since 应该为 since the rain is falling so frequently

如果选A， 应该是Since the rain falls so...,而不是falling，since后面要加完整的句子，而后面是非谓语，with可以引导非谓语。

with 表示一个状态

B
since ,as 从属连词，后接句子
for 做因为讲时，是并列连词，通常在句末，用逗号隔开
with 是介词。with+宾语+ 宾补（名词、形容词、副词、介词短语、分词、不定式）。