【正确答案】 B

【答案解析】[分析] but作为关系代词也可引导定语从句，同具有否定意义的主句连用，其先行词可以是人，也可以是物，but在意义上等于“that... not，who... not”，而且but只用于限定性定语从句中。如：There was not one house but was burnt down. 所有的房子都被烧掉了。There are few of them but admire your achievement. 他们几乎每个人都敬佩你的成就。本题如果用关系代词that，可以这样表达：There are very few rules of grammar that have no exceptions. 如果用分词应该说： There are very few rules of grammar having no exceptions.