Is that the reason ______ at the meeting for his carelessness in his work? Actually we think he is a man who

is hard ______ himself especially in work. [ ]

A. that he explained to all; on

B. what he explained all; with

C. why he explained to all; at

D. which he explained to all; to

流通企业的经营活动就是组织现有的商品进行销售来获取利润，其业务活动相对于制造企业较为简单，以进、存、销活动为主，不涉及复杂的生产物料组织，物品实体也较为单一，多为产成品。( )