单选题 ______we all know, Mr. Wang is a very warm-hearted person.
A. Which B. That C. As D. It

【正确答案】 C
【答案解析】[解析] as引导的定语从句放在句首，指主句的全部内容，主句是as we all know(众所周知)的具体内容，故选C。