Additional social stresses may also occur because of the population explosion or problems arising from mass migration movements—themselves made relatively easy nowadays by modern means of transport.

由于人口的猛增或大量人口流动（现代交通工具使这种流动相对容易）造成的种种问题也会对社会造成新的压力。

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One of the most profound trends of our time is the mass migration of the world's population into urban areas.

我们这个时代最具有深远影响的一个趋势就是全球范围内大规模向城市迁移。

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China's economic boom has triggered mass migration of rural workers to cities in search of higher incomes and better opportunities.

中国的经济繁荣导使大量农村劳动力进入城市，以寻找获得更高的收入和更好的机会。

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That crisis could potentially create a mass migration of people out of the islands.

NPR: Pacific Island Cultures Brace for Climate Change

Nevertheless, such a mass migration could change the mosaic of Pacific culture for centuries.

NPR: Pacific Island Cultures Brace for Climate Change

Today they reap the benefits of big-brand makers' mass migration away from vertical manufacturing.

FORBES: Leveling the playing field