nabla是什么意思

用法例句

Based on the current situation of the supply and demand of China s medical and health resource, this paper, with the data collected, expounds the inharmonious phenomenon of "upside-down triangle" and "regular triangle" in the first part.

文章首先基于我国当前卫生资源供需现状,用数据引出"倒三角"与"正三角"的不和谐现象。