downward mobility是什么意思

用法例句

Research results show that either based on the overall judgment or through analyzing several other indicators,such as the water sources of irrigation,water supply reliability and the changes of groundwater table,water shortage cannot be ignored.

研究发现,无论是对水资源短缺进行总体判断,还是从灌溉水源、供水可靠性和地下水位变动趋势等其它方面进行分析,水资源短缺状况都不容忽视,而且这一趋势在加重。