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.
请问如何理解粗体部分的句子?themselves 指的是massmigration movements,那themselves made可以改成 they were mande吗?
分析:根据句意,句中的反身代词 themselves 是指前面的出现的 mass migration movements(大量人口迁移),其后的过去分词短语用作定语,修饰 themselves。破折号后面的部分可以转换成 they were made relatively easy nowadays by modern means of transport,也可转换成非限制性定语从句 which were made relatively easy nowadays by modern means of transport。
句意:由于人口激猛增或大量人口迁移所引起的各种问题也会给社会造成了新的压力——现代化的交通工具使得大量人口流动变得相对容易。