nets是什么意思？

However, the cow then moved through one of the nets knocking down a police officer in the process.

By some studies, the safety nets for retirees have reduced fertility rates by 0.5 By some studies, the safety nets for retirees have reduced fertility rates by 0.5 children in the United States and almost 1.0 in Western Europe, reports economist Robert Stein in the journal National Affairs.0 in Western Europe, reports economist Robert Stein in the journal National Affairs.