“上”和“下”本是一对表空间概念的词语,常常映射到其它非空间领域,表示时间、等级、范围等意义。而在实际的语言现象中,两者并不总是对称出现的。本文把研究对象限定在“上”“下”作为方位名词时出现在介宾词组末尾的这一小类情况,即放在“在……上/下”结构中,着重分析它们在使用中表现出来的对称与不对称现象。 “On ” and “next ” This is a pair of the concept of table space, often mapped to other non-spatial areas, indicating time, level, range and other meanings. In actual linguistic phenomena, the two do not always appear symmetrically. In this paper, the research object is limited to the sub-phrase at the end of the sub-phrase when it is used as the orientation noun, that is, it is placed in the structure of “up / down”. Analyze the symmetry and asymmetry that they show in use.