The problem just ---in their diacussion is an important one.A,to be refered to B.referred to
问题描述：
The problem just ---in their diacussion is an important one.A,to be refered to B.referred to
C.referring to D.referred 选b,why
答
refer to...谈到,谈起.这里用过去分词短语作定语,表示被动关系,即the problem 是refer to动作的承受者.