如何理解这句VOA的句子Tunisia's once-vibrant economy is struggling to get back on its feet and young Tunisians continue to head in droves to Europe - prompting talk of tightening Europe's open-border Schengen agreement.前半句我明白“突尼斯的经济正努力重回正轨”,但后半句由于"head in"和"drove to"和"prompting talk of"无法理解,也搞不清楚“是促使欧洲打开边境好让他们避难”还是说“促使欧洲关闭国境”.简要说明即可,
问题描述：
如何理解这句VOA的句子
Tunisia's once-vibrant economy is struggling to get back on its feet and young Tunisians continue to head in droves to Europe - prompting talk of tightening Europe's open-border Schengen agreement.
前半句我明白“突尼斯的经济正努力重回正轨”,但后半句由于"head in"和"drove to"和"prompting talk of"无法理解,也搞不清楚“是促使欧洲打开边境好让他们避难”还是说“促使欧洲关闭国境”.
简要说明即可,
答
young Tunisians continue 年轻人继续
in droves to 成群结队
prompting talk 促使会谈
open-border Schengen agreement 开放边界的Schengen协定.根据协定,人们过界不需要签证.
大意明白了吧